SOLUTION: 3. Find all real solutions to the following: a) log2(x - 2) + log2(x + 1) = log2 10

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Question 581756: 3. Find all real solutions to the following:
a) log2(x - 2) + log2(x + 1) = log2 10

Answer by nerdybill(7384)   (Show Source): You can put this solution on YOUR website!
log2(x - 2) + log2(x + 1) = log2 10
log2(x - 2)(x + 1) = log2 10
(x - 2)(x + 1) = 10
x^2+x-2x-2 = 10
x^2-x-2 = 10
x^2-x-12 = 0
(x-4)(x+3) = 0
x = {-3, 4}
The -3 is an "extraneous" solution so we throw it out leaving:
x = 4

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