anonymous 5 years ago 81^(2x)=9 , how can I find x?

1. anonymous

4x=1

2. anonymous

x=1/4 lols

3. anonymous

Write $$81$$ as $$9^2$$. So, $$9^{4x}=9$$. Since they have the same base, they must have the same exponent. So $$4x=1$$, which gives $$x= \frac{1}{4}$$.

4. anonymous

81 = 9^2 , so 81^(2x) = (9^2)^(2x) = 9^(4x) = 9 , 4x=1 etc

5. anonymous

oh, gotcha. Than kyou :)