SAT Math Practice Question
$$(a x+3)\left(5 x^{2}-b x+4\right)=20 x^{3}-9 x^{2}-2 x+12$$The equation above is true for all $x$, where $a$ and $b$ are constants. What is the value of $a b$ ?
- A.18
- B.20
- C.24
- D.40
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