STAAR (State of Texas Assessments of Academic Readiness) Algebra I, May 2019, cont.

Continuing with the State of Texas Assessments of Academic Readiness (STAAR) exam, administered MAY 2019.

More STAAR problems.

Administered May 2019

Read each question carefully. For a multiple-choice question, determine the best answer to the question from the four answer choices provided. For a griddable question, determine the best answer to the question.





36. Which expression is equivalent to 210d² - 63d?

F 21d(10d - 3)
G 21d(10d + 3)
H 21(10d - 3)
J 21(10d + 3)

Answer: F 21d(10d - 3)^x
Simple factoring. Or use the Distributive Property on the choices.
21 is a factor of both terms. There is also a factor of d in both of those terms.
There is no reason when factoring to flip the sign from minus to plus.
Also, for either H or J to be correct, there would need to be another factor of d inside the parentheses because 21(10d) is only 210d, not 210d².



32. What is the value of x in the solution to this system of equations?

3x - 5y = 22
y = -5x + 32

A -6.5
B 0.5
C 6.5
D -0.5

Answer: C 6.5
If you do the Substitution, you get

3x - 5(-5x + 32) = 22
3x +25x - 160 = 22
28x - 160 = 22
28x = 182
x = 6.5
If you work from the choices, you have to substitute into the second equation to get y, and then substitute both x and y into the first equation to see if you get 22.

38. Which graph best represents y = 10(0.085)^x?

Answer: G
Since 0.85 is less than 1, the graph is shrinking not expanding. So Choices F and H are eliminated.

When x = 0, the initial amount is 10. The fits both G and J.
When x = 1, y = 10(0.85) = 8.5, which is graph G. Graph J is far below this, and can be eliminated.



39. The table shows a linear relationship between x and y.

What is the rate of change of y with respect to x?

A -9/2
B 2/9
C -2/9
D 9/2

Answer: A -9/2
Pick any two points. I prefer smaller numbers, easier to simplify.

m = (33 - 15) / (-6 - -2) = 18 / -4 = -9 / 2.



40. Which value of x is a solution to this equation?

5x² - 36x + 36 = 0

F x = -6
G x = 4
H x = -1.8
J x = 1.2

Answer: J x = 1.2

5x² - 36x + 36 = 0
Multiply ac: (5)(36) = 180. What are the factors of 180 that add up to -36?
Both must be negative
1 & 180, 2 & 90, 3 & 60, 4 & 45, 5 & 38, 6 & 30 < --- Stop Here

5x² - 30x - 6x + 36 = 0
(5x² - 30x) + (-6x + 36) = 0
5x(x - 6) - 6(x - 6) = 0
(5x - 6)(x - 6) = 0
5x - 6 = 0 or x - 6 = 0
5x = 6 or x = 6
x = 1.2 or x = 6

More to come. Comments and questions welcome.

More STAAR problems.