Question 711649: Solve the equation. Round answer to four decimal places.
log3(x+2)+log3(4x-1)=5?
Answer by nerdybill(7384)   (Show Source):
You can put this solution on YOUR website! log3(x+2)+log3(4x-1)=5
log3(x+2)(4x-1)=5
(x+2)(4x-1)=3^5
4x^2-x+8x-2 = 243
4x^2+7x-245 = 0
rewrite middle term:
4x^2-28x+35x-245 = 0
group:
(4x^2-28x)+(35x-245) = 0
4x(x-7)+35(x-7) = 0
(x-7)(4x+35) = 0
x = {-35/4, 7}
throw out the negative solution (extraneous) leaving:
x = 7
or, to 4 decimal places:
x = 7.0000
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