## Thursday, February 25, 2021

### STAAR (State of Texas Assessments of Academic Readiness) Algebra I, May 2017, cont.

I had to put these on hold for a while. They're back now.

More STAAR problems.

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.

16. What is the slope of the line represented by 5x - 12y = 24?

F -2
G 24/5
H -12
J 5/12

When a linear equation is written in standard form, it is Ax + By = c. In that case the slope of the line will be -A/B. In this example A = 5 and B = -12, and -5/-12 = 5/12.

Alternatively, you can rewrite the equation in slope-intercept form, y = mx + b.

5x - 12y = 24
-12y = -5x + 24
y = -5/-12 x + 24/-12
y = 5/12 x - 2

The slope is 5/12.

17. Which expression is equivalent to 6x2 + 13x + 5?

A (2x + 5)(3x - 1)
B (2x - 5)(3x + 1)
C (2x + 1)(3x + 5)
D (2x - 1)(3x - 5)

Answer: C (2x + 1)(3x + 5)
I hope you didn't waste any time factoring this example when you had four choices with three easily eliminated options.
The constant is +5, which is positive, so both of the constants in the binomials need to be the SAME sign. This eliminates A and B.
The middle term is +13x, which is positive, so both constants have to be positive. This eliminates choice D.
Choice C is the answer, which you can check by multiplying.

18. A bus travels two different routes: the Green Route and the Blue Route. The routes are different lengths.
• On Monday the bus traveled the Green Route 6 times and the Blue Route 5 times, traveling a total of 52 miles.
• On Tuesday the bus traveled the Green Route 12 times and the Blue Route 13 times, traveling a total of 119 miles.
What is the length of the Green Route in miles?

F 4.4 mi
G 4.5 mi
H 6.4 mi
J 6.8 m

Set up a system of equations and solve using elimination.

6g + 5b = 52
12g + 13b = 119
Double the first equation.
12g + 10b = 104
12g + 13b = 119
Subtract
3b = 15
b = 5
6g + 5(5) = 52
6g = 27
g = 4.5 mi

19. The table shows the heights and the lengths of several rectangles.

What does the correlation coefficient for the data indicate about the strength of the linear association between the height and the length of these rectangles?

A Weak negative correlation
B Strong negative correlation
C Weak positive correlation
D Strong positive correlation

Put the data into your graphing calculator and do a linear regression. You should get a correlation coefficient of approximately 0.15548, which is positive and very weak.

20. The expression ( x3)(x-17) is equivalent to xn. What is the value of n? Record your answer and fill in the bubbles on your answer document.