SOLUTION: 45. log (x+2)+ log (x-2)=1 5 5 47. log (4x)+ log (x+3)=log x 7 7 7

Question 135879This question is from textbook
: 45. log (x+2)+ log (x-2)=1
5 5
47. log (4x)+ log (x+3)=log x
7 7 7 This question is from textbook

Answer by edjones(8007) (Show Source): You can put this solution on YOUR website!
log[5](x+2)+log[5](x-2)=1
log[5](x+2)(x-2)=1
5^log[5](x+2)(x-2)=5^1
(x+2)(x-2)=5
x^2-4=5
x^2-9=0
(x+3)(x-3)=0
x=3
.
log[7](4x)+log[7](x+3)=log[7]x
log[7](4x)(x+3)=log[7]x
7^log[7](4x^2+12x)=7^log[7]x
4x^2+12x=x
4x^2+11x=0
x(4x+11)=0
4x=-11
x=-11/4 This is not in the domain of logrithms.
x=0 the answer is undefined.
.
Ed

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