Question
I'm having a hard time with this problem. The book tells you the answer is 5, but I don't know how they got there.
log(x+25)= 1+ log(2x-7)
log(x+25)= 1+ log(2x-7)
Answers
Steve
recall that log 1 = 10
log(x+25) = log(10) + log(2x-7)
log(x+25) = log(10(2x-7))
x+25 = 10(2x-7)
x+25 = 20x - 70
19x = 95
x = 5
check:
log(30) = 1 + log(3) = log(10)+log(3) = log(30)
log(x+25) = log(10) + log(2x-7)
log(x+25) = log(10(2x-7))
x+25 = 10(2x-7)
x+25 = 20x - 70
19x = 95
x = 5
check:
log(30) = 1 + log(3) = log(10)+log(3) = log(30)