SAT Equivalent expressions Practice Question 9 (Medium)

SAT Owl

Question bank / Equivalent expressions

Math · Advanced MathMedium

Which of the following is a factor of $2x^2 + 7x - 15$ ?

$x - 5$

$2x + 3$

$x + 5$

$2x + 5$

Show answer and explanation

Answer: C

Factor by grouping: find two numbers that multiply to $2(-15) = -30$ and add to 7, which are 10 and $-3$ . Then $2x^2 + 10x - 3x - 15 = 2x(x + 5) - 3(x + 5) = (2x - 3)(x + 5)$ .

Choice A has the wrong sign; $(x - 5)$ would make $x = 5$ a zero, but $2(25) + 35 - 15 = 70 \ne 0$ .

Ask Owl about this question Next question

Got it wrong? On SAT Owl, Owl looks at the answer you chose and explains the exact mistake, then gives you similar questions until it sticks. Get your predicted SAT score free.