## Saturday, February 27, 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.

26. The graph models the linear relationship between the temperature of Earth’s atmosphere and the altitude above sea level.

Which of these best represents the rate of change of the temperature with respect to altitude
F -6.5°C/km
G -3.5°C/km
H -0.29°C/km
J -0.15°C/km

The graph drops from about (0, 15) to (10, -50). That a 65 degree drop at a run of 10 km. -65/10 = -6.5.

27. The value of y is directly proportional to the value of x. If y = 35 when x = 140, what is the value of y when x = 70?

Read this carefully. The value of x has been cut in half. If y is directly proportional, it is also cut in half, so it will be 17.5.
Be carefulat that you didn't swap those values in your head and double 140 to 280.

28. Which expression is equivalent to m2 - 13m - 30?

F (m - 15)(m + 2)
G (m - 10)(m - 3)
H (m + 15)(m - 2)
J (m + 10)(m + 3)

Answer: F (m - 15)(m + 2)
Two factors of -30 that have a sum of -13. One must be positive and one negative. And the negative number has to have the larger magnitude (bigger absolute value). That's Choice F.
If you multiply the other binomials, you will get the same numbers, but the signs will change.

29. The line graphed on the grid represents the first of two equations in a system of linear equations.

If the graph of the second equation in the system passes through the points (-12, 20) and (4, 12), which statement is true?

A The only solution to the system is (10, 5).
B The only solution to the system is (0, 14).
C The system has no solution.
D The system has an infinite number of solutions

Answer: C The system has no solution.
If you were to plot the two points, (-12, 20) and (4, 12), you would see that each of them is 4 units above the first line. This means that second line is parallel to the first line, and there are no solutions.
"Infinite number" can be thrown out immediately because the two points were NOT on the first line.

30. What is the domain of f(x) = 9 = x2?

F f(x) ≥ 9
G All real numbers
H -3 ≤ x ≤ 3
J x ≤ 9

Don't be fooled. You are asked for domain, which are the x values, not the range, which are the values.
And there is nothing stating that f(x) must be greater than 0.
There are no restrictions on x. There is no value of x for which f(x) is undefined.

More to come. Comments and questions welcome.

More STAAR problems.