help me plz

janekela

New member
Joined
Jan 15, 2006
Messages
5
hi
well i got some homework recently but i just cant get it correct :cry:
4^x(5^2x)=10
any help at all would be appreciated :(
 
First step is to take the log of both side.

Then use the property of logs such that:

log(a*b) = log(a) + log(b)

and

log(x^y) = ylog(x)

you should end up with x = 1/2
 
Hello, janekela!

We don't need logs . . .

We have: \(\displaystyle \:(4^x)\cdot(5^{2x})\;=\;10\)

The left side is: \(\displaystyle \:[(2^2)^x]\cdot(5^{2x})\;=\;(2^{2x})(5^{2x})\;=\;(2\cdot5)^{2x}\;=\;10^{2x}\)

The equation becomes: \(\displaystyle \:10^{2x}\;=\;10^1\)

Therefore: \(\displaystyle \;2x\,=\,1\;\;\Rightarrow\;\;x\,=\,\frac{1}{2}\)
 
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