Question

How do you solve when you have logs on one side but not the other? (2 problems inside)

Answer 1

use the product rule log A + log B = log (AB)

Answer 2

I tried that...
for Log x + log (x+15) = 2
I have (Log x)(log (x+15)) =2
i dont know what to do after
The answer is 5

Answer 3

\[\lg x(x+15) = 2\]

Answer 4

convert 2 to log 100

Answer 5

log x+log (x+15)=log(x(x+15))!!

Answer 6

it just a hint, so that both sides have log's :)

Answer 7

But how do you go from
log(x(x+15)=2.. to x=5?
I can't get that part

Answer 8

log(x(x+15))=2
log(x(x+15)=log100
cancel out the log, giving us :
x(x+15)=100 or
x^2+15x-100=0
solve for x by factorization or by complete square or by quadratic formula

Answer 9

got it ?

Answer 10

Yes! Just solved it.. thank you!

Answer 11

yw

Answer 12

I didn't think of doing log 100 to cancel the logs on both sides