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2002 AMC 10B Problem 13

Problem 13 of 25IntermediateAlgebra

What value of xx makes 8xy−12y+2x−3=08xy - 12y + 2x - 3 = 0 true for all values of y?y?

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Solution

Grouping and factoring, 8xy−12y+2x−3=4y(2x−3)+(2x−3)=(4y+1)(2x−3). \begin{aligned} &8xy - 12y + 2x - 3 \\ &= 4y(2x - 3) + (2x - 3) \\ &= (4y + 1)(2x - 3). \end{aligned} For this to equal 00 for all y,y, the factor that depends on yy cannot be forced to zero, so we need 2x−3=0,2x - 3 = 0, giving x=32.x = \dfrac32. Thus, the correct answer is D.
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