## anonymous one year ago Solve1 over 25 = 5x + 4.

1. anonymous

@phi

2. anonymous

|dw:1438191114060:dw|

3. phi

is 25 a power of 5 ?

4. anonymous

yes 5^2

5. phi

do you know that 1/a can be written a^(-1) ?

6. phi

so if we let 5^2 be "a" for the moment 1/(5^2) = (5^2)^-1 $\frac{1}{5^2}= \left(5^2\right)^{-1}$ now use the rule $\left(a ^b\right)^c = a^{bc}$

7. anonymous

Ok!

8. anonymous

-5=x

9. phi

can you show the steps?

10. anonymous

(5^2)^-1=5^x+4 -1=x+4

11. anonymous

x=-5

12. anonymous

oh! I meant -6

13. phi

the left side is not correct. the rule up above says a "power to a power" ... multiply the powers you get 5^(-2) (and you really should know this: 5^(-2) is the same as 1/5^2 )

14. phi

-2 = x + 4 and yes you get x= -6

15. anonymous

Thanks :)

16. anonymous

And I do know that, I just had a brain fart

17. phi

yw