Bluebook SAT Test Nonlinear Equations and Systems — Questions and Answers
Question 1: What are the solutions to x² − 5x + 6 = 0?
- x = 2 and x = 3 (Correct answer)
- x = −2 and x = −3
- x = 1 and x = 6
- x = −1 and x = −6
Correct answer: x = 2 and x = 3
Factor as (x−2)(x−3) = 0, giving x = 2 and x = 3.
Question 2: The quadratic equation x² − 4x + k = 0 has exactly one real solution. What is the value of k?
Correct answer: 4
For exactly one solution the discriminant = 0: (−4)² − 4(1)(k) = 0 → 16 = 4k → k = 4.
Question 3: Which of the following are both solutions to 2x² + 3x − 2 = 0?
- x = 1/2 and x = −2 (Correct answer)
- x = 2 and x = −1/2
- x = 1 and x = −2
- x = 1/2 and x = 2
Correct answer: x = 1/2 and x = −2
Factor: (2x−1)(x+2) = 0 → x = 1/2 or x = −2.
Question 4: How many real solutions does the equation x² + 6x + 10 = 0 have?
- None (Correct answer)
- Exactly one
- Exactly two
- Infinitely many
Correct answer: None
Discriminant = 6² − 4(1)(10) = 36 − 40 = −4 < 0, so no real solutions exist.
Question 5: What is the vertex of the parabola y = x² − 8x + 15?
- (4, −1) (Correct answer)
- (4, 1)
- (−4, −1)
- (−4, 1)
Correct answer: (4, −1)
x-vertex = −(−8)/(2·1) = 4; y = 16 − 32 + 15 = −1; vertex = (4, −1).
Question 6: Solve for x: x² = 49
- x = 7 only
- x = −7 only
- x = 7 or x = −7 (Correct answer)
- No real solution
Correct answer: x = 7 or x = −7
Taking the square root of both sides gives x = ±7.
Question 7: The parabola y = x² + bx + c passes through (0, 5) and (5, 0). What is the value of b?
- −6 (Correct answer)
- −5
- −4
- −3
Correct answer: −6
From (0,5): c = 5. From (5,0): 25 + 5b + 5 = 0 → 5b = −30 → b = −6.
Question 8: Which values of x satisfy x² − x − 12 = 0?
- x = 4 and x = −3 (Correct answer)
- x = −4 and x = 3
- x = 6 and x = −2
- x = 3 and x = 4
Correct answer: x = 4 and x = −3
Factor: (x−4)(x+3) = 0 → x = 4 or x = −3.
Question 9: For the equation 3x² − 12x + 12 = 0, what is the value of the discriminant?
- 0 (Correct answer)
- 12
- 36
- 144
Correct answer: 0
Discriminant = (−12)² − 4(3)(12) = 144 − 144 = 0.
Question 10: Using the quadratic formula, what are the solutions of x² − 6x + 7 = 0?
- x = 3 ± √2 (Correct answer)
- x = 6 ± √2
- x = 3 ± 2√2
- x = −3 ± √2
Correct answer: x = 3 ± √2
x = [6 ± √(36−28)] / 2 = [6 ± √8] / 2 = [6 ± 2√2] / 2 = 3 ± √2.
Question 11: The system y = x² and y = x + 6 is solved by substitution. What are the x-values of the intersection points?
- x = 3 and x = −2 (Correct answer)
- x = −3 and x = 2
- x = 6 and x = −1
- x = 2 and x = −6
Correct answer: x = 3 and x = −2
Set x² = x + 6 → x² − x − 6 = 0 → (x−3)(x+2) = 0 → x = 3 or x = −2.
Question 12: How many points of intersection does the system y = x² − 3 and y = 2x have?
Correct answer: 2
x² − 3 = 2x → x² − 2x − 3 = 0; discriminant = 4 + 12 = 16 > 0, so 2 intersections.
Question 13: The function f(x) = x² − 4x + 3. At which x-value does f(x) reach its minimum?
- x = 1
- x = 2 (Correct answer)
- x = 3
- x = 4
Correct answer: x = 2
The vertex x-coordinate = 4 / (2·1) = 2; this is the minimum since a > 0.
Question 14: The system y = x + 2 and y = x² − 4 has two solutions. What is the sum of their x-coordinates?
Correct answer: 1
x² − 4 = x + 2 → x² − x − 6 = 0; by Vieta's, sum of roots = −(−1)/1 = 1.
Question 15: Using the quadratic formula, what are the solutions to 2x² − 4x − 6 = 0?
- x = 3 and x = −1 (Correct answer)
- x = 2 and x = −3
- x = 3 and x = 1
- x = −3 and x = 1
Correct answer: x = 3 and x = −1
Divide by 2: x² − 2x − 3 = 0 → (x−3)(x+1) = 0 → x = 3 or x = −1.
Question 16: The parabola y = (x − 3)² − 4 intersects the x-axis at which two values of x?
- x = 1 and x = 5 (Correct answer)
- x = 3 and x = −3
- x = 7 and x = −1
- x = 5 and x = −5
Correct answer: x = 1 and x = 5
Set y = 0: (x−3)² = 4 → x−3 = ±2 → x = 5 or x = 1.
Question 17: How many solutions does the system y = x² + 3x + 2 and y = x + 2 have?
- 0
- 1
- 2 (Correct answer)
- Infinitely many
Correct answer: 2
x² + 3x + 2 = x + 2 → x² + 2x = 0 → x(x+2) = 0 → x = 0 or x = −2; two solutions.
Question 18: The equation x² + px + 16 = 0 has two equal real roots. What is the positive value of p?
Correct answer: 8
Equal roots require discriminant = 0: p² − 64 = 0 → p = ±8; the positive value is 8.
Question 19: A parabola y = x² − 4x + c does not intersect the x-axis. Which value of c satisfies this condition?
- c = 2
- c = 4
- c = 5 (Correct answer)
- c = 1
Correct answer: c = 5
Discriminant < 0: 16 − 4c < 0 → c > 4; only c = 5 satisfies this.
Question 20: If x² − 7x + 10 = 0, what is the value of x² − 7x?
- −10 (Correct answer)
- 7
- 10
- 17
Correct answer: −10
From the equation: x² − 7x + 10 = 0 → x² − 7x = −10.
Question 21: Which of the following systems has exactly one solution?
- y = x² and y = −1
- y = x² and y = 0
- y = x² − 4 and y = −5
- y = (x−1)² and y = 0 (Correct answer)
Correct answer: y = (x−1)² and y = 0
(x−1)² = 0 → x = 1 is the only solution; all other choices yield 0 or 2 solutions.
Question 22: Which of the following is a factor of x² + 7x + 12?
- (x + 3) (Correct answer)
- (x − 3)
- (x + 6)
- (x − 4)
Correct answer: (x + 3)
x² + 7x + 12 = (x+3)(x+4), so (x+3) is a factor.
Question 23: The line y = −3x + 5 and the parabola y = x² − 4 intersect at two points. What is the product of the x-coordinates of these two points?
Correct answer: −9
x² − 4 = −3x + 5 → x² + 3x − 9 = 0; by Vieta's, product of roots = −9/1 = −9.
Question 24: What is the maximum value of the function f(x) = −x² + 4x + 1?
Correct answer: 5
Vertex x = −4/(2·(−1)) = 2; f(2) = −4 + 8 + 1 = 5.
Question 25: The equation kx² − 6x + 1 = 0 has two distinct real solutions. Which of the following must be true?
- k < 9 (Correct answer)
- k > 9
- k = 9
- k ≥ 9
Correct answer: k < 9
Discriminant > 0: 36 − 4k > 0 → k < 9.
Question 26: The roots of ax² + bx + c = 0 are both negative. If a > 0, which of the following must be true?
- b > 0 and c > 0 (Correct answer)
- b < 0 and c > 0
- b > 0 and c < 0
- b < 0 and c < 0
Correct answer: b > 0 and c > 0
Sum of roots = −b/a < 0 → b > 0; product of roots = c/a > 0 → c > 0.
Question 27: What is the y-intercept of the parabola y = 2x² − 5x + 3?
- y = −3
- y = 0
- y = 3 (Correct answer)
- y = 5
Correct answer: y = 3
Set x = 0: y = 2(0)² − 5(0) + 3 = 3.
Question 28: Solve the system y = x + 2 and y = x² by substitution. What are the x-values of the solutions?
- x = 2 and x = −1 (Correct answer)
- x = 0 and x = 2
- x = −2 and x = 1
- x = 1 and x = −2
Correct answer: x = 2 and x = −1
x² = x + 2 → x² − x − 2 = 0 → (x−2)(x+1) = 0 → x = 2 or x = −1.