2007-04-18 16:06:05 · 11 answers · asked by tracy c 1 in Science & Mathematics ➔ Mathematics
Combine the logs:
log5(x+3)=2
log(5x+15)=2
I'm assuming the logs are base 10 as no number is written, so to "cancel" the logs we do 10 to the power of each side...
5x+15=10^2
5x+15=100
5x = 85
x=17
2007-04-18 21:04:41 · answer #1 · answered by Stephen L 1 · 0⤊ 0⤋
OK try this:
log(x+3)+log5=2
= log {5 (x+3)} = 2
= log{5x + 15} = 2
= 5x + 15 = 100
5x = 85
x = 17
Hope this helps and if you like the answer vote for it!!
2007-04-19 10:31:25 · answer #2 · answered by Anonymous · 0⤊ 0⤋
log (x+3) + log 5 = 2
Combining the logs,
Log (5x + 15) = 2
(I assume it's log base 10)
5x + 15 = 100
5x = 85
x = 17
2007-04-19 08:34:26 · answer #3 · answered by kkoh 2 · 0⤊ 0⤋
Generally log(a)+log(b)=log(ab)
k=log10^κ
and if logx=logy then x=y
then, you have log(x+3)+log5=2
log5(x+3)=2
log(5x+15)=log10²
log(5x+15)=log100
5x+15=100
5x=85
x=85/5
χ=17
2007-04-22 01:05:39 · answer #4 · answered by Kulubaki 3 · 0⤊ 0⤋
log(x+3) + log5 = 2
log[(x+3)(5)] = 2
log[5x+15] = 2
5x + 15 = 10^2
5x + 15 = 100
5x = 100 - 15
5x = 85
x = 85 / 5
x = 17
2007-04-21 04:24:32 · answer #5 · answered by Kemmy 6 · 0⤊ 0⤋
Assume log base 10
log 5.(x + 3) = 2
5.(x + 3) = 10²
5x + 15 = 100
5x = 85
x = 17
2007-04-19 09:50:11 · answer #6 · answered by Como 7 · 0⤊ 0⤋
when adding logs you multiply the numbers together
so,
log( 5(x+3) ) = 2
if the logs are to base 10 then it means 10^2 = 5(x+3)
100= 5x + 15
x=17
2007-04-19 06:53:49 · answer #7 · answered by Anonymous · 0⤊ 0⤋
x = 17
2007-04-18 16:10:39 · answer #8 · answered by CRAZYDEADMOTH 3 · 0⤊ 0⤋
log(x+3)+log5=2
log(5x+15)=2log10
5x+15=100
x=17
2007-04-18 23:06:58 · answer #9 · answered by intelli 1 · 0⤊ 0⤋
log(x+3)+log5 = log(5(x+3)) = 2log(5x+15)^0.5,
that is 2log(square root of(5x+15))
2007-04-22 10:48:12 · answer #10 · answered by Michael Schumann 1 · 0⤊ 0⤋