How do you solve #10^x=5^(x+1)#?

2 Answers
May 7, 2016

#x=log 5/log 2#.

Explanation:

#10^x=(2 X 5)^x=2^x5^x=5^(x+1)=5^x5^1#.

Cancelling the common factor #5^x#,

#2^x=5#.

Equating the logarithms,

#x log 2 = log 5#.

So, #x=log 5/log 2#.

I found: #x=2.32193#

Explanation:

We can try taking the natural log of both sides and apply one property of logs to write:
#ln(10^x)=ln(5^(x+1))#
and then for the exponents:
#xln(10)=(x+1)ln(5)#
rearrange:
#xln(10)=xln(5)+ln(5)#
#xln(10)-xln(5)=ln(5)#
so:
#x[ln(10)-ln(5)]=ln(5)#
and:
#x=(ln(5))/(ln(10)-ln(5))=ln5/ln(10/5)=ln5/ln2=2.32193#