2002 AMC 12A Problem 1

Attempt Problem 1 of the 2002 AMC 12A below, then check your answer against the professionally curated solution from LIVE by Po-Shen Loh. You can also try the full timed exam, view all 2002 AMC 12A solutions, or check the answer key.

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1.

Compute the sum of all the roots of (2x+3)(x4)+(2x+3)(x6)=0. \begin{aligned} &(2x+3)(x-4) \\ &\quad {}+(2x+3)(x-6)=0. \end{aligned}

72\dfrac{7}{2}

44

55

77

1313

Answer: A
Concepts:factoringVieta’s Formulas
Difficulty rating: 890
Solution:

Factoring out 2x+32x+3 gives (2x+3)[(x4)+(x6)](2x+3)\big[(x-4)+(x-6)\big] =(2x+3)(2x10)= (2x+3)(2x-10) =0.= 0.

The roots are 32-\dfrac{3}{2} and 5,5, whose sum is 32+5=72.-\dfrac{3}{2} + 5 = \dfrac{7}{2}.

Thus, the correct answer is A.

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