Saturday, February 22, 2025

Algebra Problems of the Day (Algebra Regents, January 2025 Part IV)


This exam was adminstered in January 2025.

January 2025 Algebra, Part IV

A correct answer is worth up to 6 credits. Partial credit can be given. Work must be shown or explained.

35. Anna plans to spend $30 on balloons and party hats for her daughter’s birthday party. Including tax, balloons cost $2 each and party hats cost $1.50 each. The number of party hats Anna needs is twice as many as the number of balloons.

If x represents the number of balloons and y represents the number of party hats, write a system of equations that can be used to represent this situation.

Graph your system of equations on the set of axes below.

State the coordinates of the point of intersection of your lines.

Explain what each coordinate means in the context of the problem.

Answer:


Write the system of equations for the number of balloons and hats and for the price of the balloons and hats. Then rewrite them solving for y in terms of x (isolate the y variable) so you can put them into your graphing calculator or graph using the slope and intercept.

This question may be confusing to anyone who did a lot of test prep because it seems like it should be an inequality question, but it is NOT.

y = 2x
2x + 1.50y = 30

1.5y = -2x + 30
y = -4/3x + 20

The graph would look as follows:

The coordinates of the solution are (6,12).

In the context of the problem, there will be 12 hats and 6 balloons.

End of Part Exam

How did you do?

Questions, comments and corrections welcome.

I also write Fiction!


The NEW COLLECTION IS AVIALABLE! A Bucket Full of Moonlight, written by Christopher J. Burke, contains 30+ pieces of short stories and flash fiction. It's available from eSpec Books!
Order the softcover or ebook at Amazon.

Vampires, werewolves, angels, demons, used-car salesmen, fairies, superheroes, space and time travel, and little gray aliens talking to rock creatures and living plants.

My older books include my Burke's Lore Briefs series and In A Flash 2020.

If you enjoy my books, please consider leaving a rating or review on Amazon or on Good Reads. Thank you!



Friday, February 21, 2025

Algebra Problems of the Day (Algebra Regents, January 2025 Part III)


This exam was adminstered in January 2025.

January 2025 Algebra, Part III

Each correct answer is worth up to 4 credits. Partial credit can be given. Work must be shown or explained.

31. Alex had $1.70 in nickels and dimes on his desk. There were 25 coins in all. Write a system of equations that could be used to determine both the number of nickels, n, and the number of dimes, d, that Alex had.

Use your system of equations to algebraically determine both the number of nickels and the number of dimes that he had.

Answer:


Write the system of equations for the number of nickels and dimes and the value of the nickels and dimes. Then solve the system.

.05n + .10d = 1.70
n + d = 25

.5n + d = 17.0
n + d = 25

.5n = 8
n = 16

16 + d = 25
d = 9

Alex has 16 nickels and 9 dimes.



32. The table below shows the average heart rate, x, and Calories burned, y, for seven men on an Olympic rowing team during a one-hour workout class.

Write the linear regression equation that models these data, rounding all values to the nearest tenth.

State the correlation coefficient, rounded to the nearest tenth.

State what the correlation coefficient suggests about the linear fit of these data.

Answer:


Put the data into the L1 and L2 in your graphing calculator and run a linear regressions.

Rounding to the nearest tenth, you'll get y = 9.1x - 527.6. Remember to write the equation. Put just write a = 9.1 and b = 527.6.

If the correlation coefficient didn't appear on your screen, go to the Catalogue and run "DiagnosticOn" and do the regression a second time.

To the nearest tenth, r = 0.9.

This suggests that there is a strong positive correlation between average heart rate and calories burned.



33. Using the quadratic formula, solve x2 + 4x - 3 = 0.
Express your solution in simplest radical form.

Answer:


The equation is in the back of the booklet. (Lucky you -- back in my century, we had to memorize it!)

x = (-b + √(b2 - 4ac)) / (2a)

x = (-4 + √(42 - 4(1)(-3)) / (2(1))

x = (-4 + √(16 + 12)) / 2

x = (-4 + √(28)) / 2

x = (-4 + (√(4)*√(7)) / 2

x = (-4 + 2√(7)) / 2

x = -2 + √(7)

The next to last line would have been an acceptable answer.



34. Solve the following system of equations algebraically for all values of x and y.

y = x2 - 7x + 12
y = 2x - 6

Answer:


Set the two expressions equal to each other and then solve the quadratic equation. Then solve for y for each value of x.

x2 - 7x + 12 = 2x - 6
x2 - 9x + 18 = 0
(x - 3)(x - 6) = 0
x - 3 = 0 or x - 6 = 0
x = 3 or x = 6

If x = 3: y = 2(3) - 6 = 0
If x = 6: y = 2(6) - 6 = 6.

End of Part III

How did you do?

Questions, comments and corrections welcome.

I also write Fiction!


The NEW COLLECTION IS AVIALABLE! A Bucket Full of Moonlight, written by Christopher J. Burke, contains 30+ pieces of short stories and flash fiction. It's available from eSpec Books!
Order the softcover or ebook at Amazon.

Vampires, werewolves, angels, demons, used-car salesmen, fairies, superheroes, space and time travel, and little gray aliens talking to rock creatures and living plants.

My older books include my Burke's Lore Briefs series and In A Flash 2020.

If you enjoy my books, please consider leaving a rating or review on Amazon or on Good Reads. Thank you!



Thursday, February 20, 2025

Algebra Problems of the Day (Algebra Regents, January 2025 Part II)


This exam was adminstered in January 2025.

January 2025 Algebra, Part II

Each correct answer is worth up to 2 credits. Partial credit can be given. Work must be shown or explained.

25. The graph below models Sally’s drive to the store.


State an interval when Sally is traveling at a constant speed. Explain your reasoning

Answer:


Sally's spped is the y-coodinate, so a constant speed means a horizontal line, not a line with a constant slope.

From 5 hours to 9 hours, Sally is driving at a constant speed of 35 mph as indicated by the horizontal line. The rate of change is 0.



26. Graph the function f(x) = x2 + 4x + 3.

Sate the equation of the axis of symmetry of f(x).

Answer:


Use your calculator to find the table of values for the parabola. The axis of symmetry is the vertical line that goes through the vertex of the graph and has the equation x = -b/(2a).

The following points are on the graph (-4,3), (-3,0), (-2,-1), (-1,0) and (0,3). Plot these and draw the curve. Remember to put arrows at the end because the graph continues upward.

The access of symmetry is x = -4/(2(1), which is x = -2.

This question is only worth two points, so if you gave the vertex instead of the axis, you didn't get any credit.



27. The function f(x) is shown in the table below.


State an appropriate value for m in the table, so that f(x) remains a function. Explain your reasoning.

Answer:


The relation is a function as long as the x values do not repeat. (Again! I wrote this very same comment in June 2024 and August 2024 for Question 27!)

Therefore, m can have any value except 0, 1, 2, 3, 4, 5, or 6, which are already used. Valid values include 7, 8, 9, or larger; -1, -2, -3, or lower; 1.5, 6 1/2, π.

You are not being asked to define the function or predict what the next value should be.

Reason: the number you selected has not already been used in the table as a value of x. The values of x cannot be repeated in a function.



28. Solve x2 + 8x = 33 for x by completing the square.

Answer:


You must complete the square. Any other method, so long as it yields the correct answer, is only worth 1 point.

The square of a binomial, such as (x + n)2, looks like x2 + 2n + n2. So the middle term of the quadratic expression is 2n and the original n is half as much.

Half of 8 is 4, so the binomial that is being squared is (x + 4).

If you square (x + 4), you get x2 + 8x + 16, so to "COMPLETE THE SQUARE", we need to add 16 to both sides of the equation: x2 + 8x + 16 = 33 + 16.

Factor this into: (x + 4)2 = 49.

Now you can solve this:

(x + 4)2 = 49
x + 4 = + 7
x = 7 - 4 or x = -7 - 4
x = 3 or x = -11



29. If f(x) = (-3x - 5)/2, algebraically determine the value of x when f(x) = -22

Answer:
Note that the problem does NOT say x = -22, what is f(-22)? The question says if f(x) = -22, then what is x?

Replace f(x) with (-3x - 5)/2 in the equation, like this:

(-3x - 5)/2 = -22
-3x - 5 = - 44
-3x = -39
x = 13

If you evaluated f(-22) = 30.5, you received half credit.



30. Rationalize the denominator of the fraction below. Express the solution in simplest form.

4 / √(2)

Answer:
Multiply the fraction by √(2) / √(2) to rationalize the denominator, and then reduce the fraction.

4 / √(2) * √(2) / √(2) = 4 √(2) / 2 = 2 √(2)

End of Part II

How did you do?

Questions, comments and corrections welcome.

I also write Fiction!


The NEW COLLECTION IS AVIALABLE! A Bucket Full of Moonlight, written by Christopher J. Burke, contains 30+ pieces of short stories and flash fiction. It's available from eSpec Books!
Order the softcover or ebook at Amazon.

Vampires, werewolves, angels, demons, used-car salesmen, fairies, superheroes, space and time travel, and little gray aliens talking to rock creatures and living plants.

My older books include my Burke's Lore Briefs series and In A Flash 2020.

If you enjoy my books, please consider leaving a rating or review on Amazon or on Good Reads. Thank you!



Sunday, February 02, 2025

Algebra 2 Problems of the Day (Algebra 2 Regents, August 2024 Part I)



This exam was adminstered in August 2024.

More Regents problems.

August 2024 Algebra 2 Regents

Part I

Each correct answer will receive 2 credits. No partial credit.


17. Given q(x) = 2log(x) and r(x) = (x - 2)3 - 4, what is a solution of q(x) = r(x) to the nearest tenth?

(1) 1.1
(2) 3.7
(3) 3.9
(4) 4.3

Answer: (2) 3.7


This is a MULTIPLE-CHOICE question. Do not attempt to solve it algebraically. It will NOT be a fun time.

You can graph both equations on your calculator and look for the point where they intersect. (There's actually a function on the calculator that will help you find it if you know how to use it.)

You can also find the values of q(1.1), r(1.1), q(3.7), r(3.7), etc to find the ones that are the same.

Let's do this just for giggles:

q(1.1) = 0.08, r(1.1) = -4.7

q(3.7) = 1.1, r(3.7) = .91

q(3.9) = 1.2, r(3.9) = 2.9

q(4.3) = 1.7, r(4.3) = 8.2

You will notice that when x = 3.7, the values of q(x) and r(x) are the closest. They differ because of rounding. (I did a little experimenting so that you wouldn't have to, and found that x = 3.725 is pretty close but still not exact.)

Choice (2) is the correct answer.

How would I solve this algebraically? I wouldn't. Simple as that.

If you would like to, please place it in the comments.




18. The volume of a cardboard box can be modeled by V(x), which is the product of the length, width, and height, x. If the length can be represented by L(x) = 18 - 2x and the width can be represented by W(x) = 18 - 2x, then which function represents V(x)?

(1) V(x) = 4x2 - 72x + 324
(2) V(x) = 4x3 - 72x2 + 324x
(3) V(x) = -3x + 36
(4) V(x) = 4x3 + 324x

Answer: (2) V(x) = 4x3 - 72x2 + 324x


It should be "obvious" that since we have to multiply three terms with the variable x in them that the final formula will contain x3 in it.

V = (18 - 2x)(18 - 2x)(x)
= (324 - 36x - 36x + 4x2)(x)
= 324x - 72x2 + 4x3

Choice (2) is the correct choice.

Choice (4) is missing the middle term. Choice (1) is the Area of the base. Choice (3) is nonsense because it just added the three expressions.




19. The expression 8x/2 * 8x/3 is equivalent to

(1) 6√(85x)
(2) 64(5x/6)
(3) 5√(82x)
(4) 64(x2/6)

Answer: (1) 6√(85x)


Keep the base and add the exponents x/2 + x/3.

The common denominator is 6, so 3x/6 + 2x/6 = 5x/6, and the expression will be 85x/6, which is not one of the listed choices.

However, the one-sixth power is the same as taking the sixth root of the expressions.

Therefore, 85x/6 is the same as (85x)(1/6 which is the same as 6√(85x). This is Choice (1).




20. If θ is an angle in standard position whose terminal side passes through the point (-3,-4), which statement is true?

(1) sec θ > 0 and tan θ > 0
(2) sec θ < 0 and tan θ < 0
(3) sec θ > 0 and tan θ < 0
(4) sec θ < 0 and tan θ > 0

Answer: (4) sec θ < 0 and tan θ > 0


Point (-3,-4) is in Quadrant III where sin is negative, cos is negative, and tan is positive. Eliminate Choices (2) and (3).

Sec = 1/cos and has the same sign and cos, which is negative in Quadrant III. So the correct answer is Choice (4).




21. What is the value of y for the system shown below?
3x + 4y - 5z = -27
2x + 3y - z = -3
6x - y + 4z = 3


(1) -27
(2) 6
(3) 3
(4) -3

Answer: (3) 3


Solve the system of equations by eliminating the x term first since 2 and 3 are factors of 6.

3x + 4y - 5z = -27
2x + 3y - z = -3
6x - y + 4z = 3

6x + 8y - 10z = -54
6x + 9y - 3z = -9
6x - y + 4z = 3

First 2 equations: y + 7z = 45
Last 2 equations: 10y - 7y = -12
Combined: 11y = 33
y = 3

Choice (3) is the correct answer.




22. The number of employees who work nights and weekends at a department store is summarized in the table below.

Let N represent the event “works nights” and let W represent the event “works weekends.” Based on the table, are N and W independent events?

(1) Yes, because P(N) • P(W) = P(N ∩ W).
(2) Yes, because P(N) • P(W) =/= P(N ∩ W).
(3) No, because P(N) • P(W) = P(N ∩ W).
(4) No, because P(N) • P(W) =/= P(N ∩ W).

Answer: (1) Yes, because P(N) • P(W) = P(N ∩ W).


The answer is either Yes because they are equal or No because they are not equal. Multiply the probabilities.

There are a total of 120 employees. P(N) = 20/120 and P(W) = 48/120, and (20/120)(48/120) = (1/6)(2/5) = 1/15.

P(N ∩ W) = 8/120 = 1/15.

So P(N) • P(W) = P(N ∩ W).

The correct answer is Choice (1).




23. Which expression is equivalent to x8 - y8?

(1) (x - y)8
(2) (x2 + y2)2(x2 - y2)2
(3) (x4 + y4)(x2 + y2)(x + y)(x - y)
(4) (x + y)4(x - y)4

Answer: (3) (x4 + y4)(x2 + y2)(x + y)(x - y)


The given expression is a Difference of Perfect Squares and canb be factored into two conjugates. One of those factors will still be a Difference of Perfect Squares and can be factored again. And then again.

x8 - y8
(x4 + y4)(x4 - y4)
(x4 + y4)(x2 + y2)(x2 - y2)
(x4 + y4)(x2 + y2)(x + y)(x - y)

The correct answer is Choice (3).

If you factor Choice (1), you will find that it is equivalent to Choice (4), so both could be eliminated.




24. A research assistant receives a first year salary of $90,000 and a 2% annual raise throughout the first ten years of employment. In total, how much money will be earned over the first ten years, to the nearest dollar?

(1) $91,837
(2) $109,709
(3) $877,917
(4) $985,475

Answer: (4) $985,475


Using the formula for a Geometric Series: Sn = (a1 - a1rn) / (1 - r), we can calculate the answer.

S10 = (90000 - 90000*1.0210) / (1 - 1.02) = 985474.89, which is Choice (4).

End of Part I. How did you do?


Comments and questions welcome.

I also write Fiction!


The NEW COLLECTION IS AVIALABLE! A Bucket Full of Moonlight, written by Christopher J. Burke, contains 30+ pieces of short stories and flash fiction. It's available from eSpec Books!
Order the softcover or ebook at Amazon.

Vampires, werewolves, angels, demons, used-car salesmen, fairies, superheroes, space and time travel, and little gray aliens talking to rock creatures and living plants.

My older books include my Burke's Lore Briefs series and In A Flash 2020.

If you enjoy my books, please consider leaving a rating or review on Amazon or on Good Reads. Thank you!



Saturday, February 01, 2025

Algebra 2 Problems of the Day (Algebra 2 Regents, August 2024 Part I)



This exam was adminstered in August 2024.

More Regents problems.

August 2024 Algebra 2 Regents

Part I

Each correct answer will receive 2 credits. No partial credit.


9. The asymptote of the graph of f(x) = 5 log(x + 4) is

(1) y = 6
(2) x = -4
(3) x = 4
(4) y = 5

Answer: (2) x = -4


First of all, you can graph this and look. Second, the asymptote will be a vertical line, which means it starts with "x = ", so eliminate Choices (1) and (4).

The asymptote of f(x) = log x is the y-axis, which is x = 0. Multiplying by 5 will not change the asymptote. However, adding 4 inside the parentheses, that is log(x + 4), will move the asymptote 4 units to the left, to x = -4. Choice (2) is the correct answer.




10. The probability of having math homework is 1/3 and the probability of having English homework is 1/7. The probability of having math homework or having English homework is 9/21. What is the probability of having math homework and having English homework?

(1) 19/21
(2) 1/5
(3) 1/21
(4) 10/21

Answer: (3) 1/21


P(M) + P(E) - P(M|E) = 1/3 + 1/7 - 9/21 = 7/21 + 3/21 - 9/21 = 1/21

Choice (3) is the correct choice.




11. The solution set to the equation x - 1 = √(2x + 6) is

(1) {5, -1}
(2) {5}
(3) {-1}
(4) { }

Answer:(2) {5}


You can check each of the listed answers to see if either, or both work.

For x = 5, 5 - 1 = 4 and √(2(5) + 6) = 4, so the answer is either Choice (1) or (2).

For x = -1, -1 -1 = -2, which cannot be the result of a square root. Eliminate Choices (1) and (3).

Choice (1) is the correct answer.

If you tried to solve it algebraically:

x - 1 = √(2x + 6)
x2 - 2x + 1 = 2x + 6
x2 - 4x - 5 = 0
(x - 5)(x + 1) = 0
x = 5 or x = -1

However, when we test the answers, we see that x = -1 must be discarded as extraneous, and only x = 5 is correct.




12. Given x > 0, the expression (1 / x-2)(-3/4) is equivalent to

(1) x √(x)
(2) 1 / (x √(x))
(3) ∛x2
(4) 1 / (∛x2)

Answer: (2) 1 / (x √(x))


Use the rules for exponents to evaluate the expression.

(1 / x-2)(-3/4)
(x2)(-3/4)
(x(-3/2))
1 / x3/2
1 / √(x3 = 1 / x √(x)

Choice (2) is the correct answer.




13. The graph of which function has a period of 3?

(1) y = -7sin(2π/3 x) - 5
(2) y = -7sin(3π/2 x) + 9
(3) y = -7sin(3x) - 5
(4) y = 3sin(π x) + 9

Answer: (1) y = -7sin(2π/3 x) - 5


Once again, you can graph these equations and look to see which is correct.

The period of y = A sin(x) + C is 2π. The period of y = A sin(Bx) + C is 2π/B.

In Choice (1), 2π/ (2π/3) = 3. This is the correct answer.

In Choice (2), 2π/ (3π/2) = 4/3. Eliminate Choice (2).

In Choice (3), 2π/ 3 is not equal to 3. Eliminate Choice (3).

In Choice (4), 2π/ (π) = 2. Eliminate Choice (4).




14. Which graph could represent a 4th degree polynomial function with a positive leading coefficient, 2 real zeros, and 2 imaginary zeros?

Answer: (1) [See image]


A positive leading coefficient on a fourth-degree polynomial means that the end behavior is toward positive infinity on both ends. Eliminate Choices (3) and (4).

Two real zeroes means that the graph crosses the x-axis in two locations, which eliminates Choice (4) and leaves Choice (1).

Since there are only two real zeroes, there must be two imaginary zeroes as well.




15. Given i is the imaginary unit, which expression is equivalent to 5i(2x + 3i) - x√(-9)?

(1) 15 + 13xi
(2) -15 + 13xi
(3) 15 + 7xi
(4) -15 + 7xi

Answer: (4) -15 + 7xi


Use the Distributive Property and the Order of Operations. Don't forget that i2 = -1 and that √(-1) = i.

5i(2x + 3i) - x√(-9)
10xi + 15i2 - 3xi
-15 + 7xi

The correct answer is Choice (4).




16. 6 What is the focus of the parabola 8(y + 2) = (x + 5)2?

(1) (-5,0)
(2) (-5,-4)
(3) (5,0)
(4) (5,4)

Answer: (1) (-5,0)


The vertex form of a parabola is y = a(x - h) + k, and the focus of the parabola is at point (h, k + 1/(4a)). Rewrite the equation in vertex form.

8(y + 2) = (x + 5)2

y + 2 = (1/8)(x + 5)2

y = (1/8)(x + 5)2 - 2

If a = 1/8, then 1/(4a) = 1/(4(1/8)) = 1/(1/2) = 2.

So (h, k + 1/(4a)) = (-5, -2+2) = (-5,0).


More to come. Comments and questions welcome.

I also write Fiction!


The NEW COLLECTION IS AVIALABLE! A Bucket Full of Moonlight, written by Christopher J. Burke, contains 30+ pieces of short stories and flash fiction. It's available from eSpec Books!
Order the softcover or ebook at Amazon.

Vampires, werewolves, angels, demons, used-car salesmen, fairies, superheroes, space and time travel, and little gray aliens talking to rock creatures and living plants.

My older books include my Burke's Lore Briefs series and In A Flash 2020.

If you enjoy my books, please consider leaving a rating or review on Amazon or on Good Reads. Thank you!