Nonlinear Equations and Systems Flashcards
7 cards from real Bluebook SAT Test practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.
Read the first 7 Nonlinear Equations and Systems flashcards as text
Which of the following is a solution to x² − x − 6 > 0?
Answer: x = 4
x² − x − 6 = (x − 3)(x + 2); this is > 0 when x > 3 or x 3.
What is the axis of symmetry for y = 3x² + 18x + 7?
Answer: x = −3
Axis of symmetry: x = −b/(2a) = −18/6 = −3.
The sum of a positive integer and its square is 42. What is the integer?
Answer: 6
n + n² = 42 → n² + n − 42 = 0 → (n + 7)(n − 6) = 0; positive solution is n = 6.
The revenue from selling x units is R(x) = −2x² + 40x. What number of units maximizes revenue?
Answer: 10 units
Maximum at vertex: x = −40/(2 × −2) = −40/−4 = 10 units.
Which of the following is equivalent to x² − 6x + 8?
Answer: (x − 2)(x − 4)
(x − 2)(x − 4) = x² − 6x + 8. ✓
For the equation x² + 5x = 14, what are both solutions?
Answer: x = −7 and x = 2
x² + 5x − 14 = 0 → (x + 7)(x − 2) = 0; x = −7 or x = 2.
The parabola y = (x + 4)(x − 2) intersects the y-axis at which point?
Answer: (0, −8)
At x = 0: y = (4)(−2) = −8; y-intercept is (0, −8).