Friday, August 8, 2014

Solve for x ? 2lg x=lg(3x-2)

First, we'll use the power property of logarithms for the left term:


2lg x = lg(x^2)


We'll re-write the equation:


lg(x^2) = lg(3x-2)


We'll use the one to one property:


x^2 = 3x-2


We'll move all termsto the left side:


x^2 - 3x + 2 = 0


We'll use the quadratic formula:


x1 = [3+sqrt(9-8)]/2


x1 = (3+1)/2


x1 = 2


x2 = 1


We'll verify the results into equation:


2lg x1=lg(3x1 - 2)


2lg2 = lg(6-2)


lg 2^2 = lg4


lg4 = lg4


2lg x2=lg(3x2 - 2)


2lg 1=lg(3-2)


2*0 = lg 1


0 = 0


So, both values of x are the solutions of the equation:


x1 = 2 and x2 = 1

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