SAT Nonlinear equations in one variable and systems of equations in two variables Practice Question 8 (Medium)

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Question bank / Nonlinear equations in one variable and systems of equations in two variables

Math · Advanced MathMedium

What is the sum of the solutions to the equation $x^2 - 10x + 21 = 0$ ?

$-10$

$7$

$10$

$21$

Show answer and explanation

Answer: C

Factor: $(x - 3)(x - 7) = 0$ , so the solutions are 3 and 7. Their sum is 10.

Choice A uses the coefficient $-10$ without changing its sign; the sum of the solutions of $x^2 + bx + c = 0$ is $-b$ .

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