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
The sum of a number and its square is 56. Which equation models this situation?
Answer: x² + x − 56 = 0
Let the number be x; x + x² = 56 rearranges to x² + x − 56 = 0.
For the equation 4x² − 20x + 25 = 0, how many real solutions are there?
Answer: 1
Discriminant = (−20)² − 4(4)(25) = 400 − 400 = 0, so exactly one repeated real solution.
What is the solution set of x² − 9 = 0?
Answer: {3, −3}
x² = 9 → x = ±3.
The system y = x² − 2x − 3 and y = 5 is solved. What are the x-values of the intersections?
Answer: x = 4 and x = −2
x² − 2x − 3 = 5 → x² − 2x − 8 = 0 → (x−4)(x+2) = 0 → x = 4 or x = −2.
A ball is thrown upward; its height in feet at time t seconds is h(t) = −16t² + 64t. At what time does the ball return to the ground (h = 0, t > 0)?
Answer: t = 4 s
−16t² + 64t = 0 → −16t(t−4) = 0 → t = 0 or t = 4; the ball returns at t = 4 s.
If the graph of y = x² + bx + 4 touches the x-axis at exactly one point, which of the following could be a value of b?
Answer: b = 4
For one x-intercept, discriminant = 0: b² − 16 = 0 → b = ±4; so b = 4 works.
Solve: (x + 2)(x − 5) = 0
Answer: x = −2 and x = 5
Set each factor to zero: x + 2 = 0 → x = −2; x − 5 = 0 → x = 5.