Bluebook SAT Test Linear Functions 3 — Questions and Answers
Question 1: A line with equation y = kx − 4 passes through the point (3, 8). What is the value of k?
- 3
- 4 (Correct answer)
- 12
- −4/3
Correct answer: 4
Substitute (3, 8): 8 = 3k − 4 → 3k = 12 → k = 4.
Question 2: The rate of change of a linear function is 5 and f(2) = 11. What is f(0)?
- 1 (Correct answer)
- 6
- 21
- −10
Correct answer: 1
f(x) = 5x + b; 11 = 5(2) + b → b = 1, so f(0) = 1.
Question 3: Line p is parallel to the line y = 3x − 7 and passes through (1, 2). What is the equation of line p?
- y = 3x + 5
- y = 3x − 1 (Correct answer)
- y = −(1/3)x + 2
- y = 3x − 2
Correct answer: y = 3x − 1
Parallel lines have equal slopes; using slope 3 and point (1, 2): 2 = 3(1) + b → b = −1, so y = 3x − 1.
Question 4: A cell phone plan charges a monthly base fee of $25 plus $0.10 per text message. If a customer's bill is $37, how many text messages did they send?
- 90
- 100
- 120 (Correct answer)
- 370
Correct answer: 120
25 + 0.10t = 37 → 0.10t = 12 → t = 120 text messages.
Question 5: The graph below has a y-intercept of 4 and passes through (2, 0). What is the slope of the line?
- 2
- −2 (Correct answer)
- −1/2
- 1/2
Correct answer: −2
Slope = (0 − 4)/(2 − 0) = −4/2 = −2.
Question 6: If f is a linear function and f(−1) = 7 and f(3) = −1, what is f(1)?
- 1
- 3 (Correct answer)
- 4
- 5
Correct answer: 3
Slope = (−1 − 7)/(3 − (−1)) = −8/4 = −2; using f(−1) = 7: 7 = −2(−1) + b → b = 5; f(1) = −2(1) + 5 = 3.
Question 7: In the equation y = 2x + c, the line passes through the origin. What is the value of c?
- −2
- 0 (Correct answer)
- 1
- 2
Correct answer: 0
Passing through the origin means (0, 0) is on the line; 0 = 2(0) + c → c = 0.
Bluebook SAT Test Linear Functions 3
A line with equation y = kx − 4 passes through the point (3, 8).
What is the value of k?