# indices (i think)

• Dec 8th 2009, 06:35 AM
andyboy179
indices (i think)
hi this is my question:

(5^3)^2 X 25^2

i have no idea how to do this
• Dec 8th 2009, 06:44 AM
e^(i*pi)
Quote:

Originally Posted by andyboy179
hi this is my question:

(5^3)^2 X 25^2

i have no idea how to do this

$5^6 \times 5^4 = 5^{10} = 9 765 625$
• Dec 8th 2009, 06:46 AM
craig
Quote:

Originally Posted by andyboy179
hi this is my question:

(5^3)^2 x 25^2

i have no idea how to do this

Do you want to solve $(5^3)^2 \times 25^2$ and get a numeric solution?

$(5^3)^2 = 5^{3\times 2} = 5^6$

Also note that $25 = 5^2$, this means that $25^2 = (5^2)^2 = 5^4$.

Following through with what I've done above, can you get $(5^3)^2 \times 25^2$ in terms of $5^n$, where $n$ is just an integer (whole number) ?
• Dec 8th 2009, 06:51 AM
andyboy179
thank you very much for answering!!!

how would i work out 25^3 divided by 5^-4?
• Dec 8th 2009, 06:54 AM
craig
Quote:

Originally Posted by andyboy179
thank you very much for answering!!!

how would i work out 25^3 divided by 5^-4?

Use what I said above to get $25^3$ in terms of $5^n$.

Also notice that $5^n \times 5^m = 5^{n+m}$.

This also applies for division, $\frac{5^n}{5^m} = 5^{n-m}$.

Another thing, do not just post questions and hope for the answer, show us your working so far and where you have got stuck, then we can help you.
• Dec 8th 2009, 07:02 AM
andyboy179
Quote:

Originally Posted by craig
Use what I said above to get $25^3$ in terms of $5^n$.

Also notice that $5^n \times 5^m = 5^{n+m}$.

This also applies for division, $\frac{5^n}{5^m} = 5^{n-m}$.

Another thing, do not just post questions and hope for the answer, show us your working so far and where you have got stuck, then we can help you.

would 25^3= 5^6?

and could you explain what to do on 5^-4???
• Dec 8th 2009, 07:03 AM
e^(i*pi)
Quote:

Originally Posted by andyboy179
would 25^3= 5^6?

Yes

Quote:

and could you explain what to do on 5^-4???
Recall that for $a^{-b} = \frac{1}{a^b}$
• Dec 8th 2009, 07:03 AM
craig
Quote:

Originally Posted by andyboy179
would 25^3= 5^6?

Correct!

Quote:

Originally Posted by andyboy179
and could you explain what to do on 5^-4???

Use the fact that $\frac{5^n}{5^m} = 5^{n-m}$, just remember that it's a minus 4 you are using, not 4.
• Dec 8th 2009, 07:07 AM
andyboy179
5^-4= -25^-2 ???
• Dec 8th 2009, 07:08 AM
e^(i*pi)
Quote:

Originally Posted by andyboy179
5^-4= -25^-2 ???

Not quite, the exponent is fine but consider the sign on $25^{-2}$
• Dec 8th 2009, 07:11 AM
andyboy179
Quote:

Originally Posted by e^(i*pi)
Not quite, the exponent is fine but consider the sign on $25^{-2}$

so would i just be -25^2
• Dec 8th 2009, 07:21 AM
craig
$\frac{25^3}{5^{-4}}$

$\frac{5^6}{5^{-4}} = 5^{6-(-4)} =$??
• Dec 8th 2009, 07:25 AM
andyboy179
Quote:

Originally Posted by craig
$\frac{25^3}{5^{-4}}$

$\frac{5^6}{5^{-4}} = 5^{6-(-4)} =$??

what so i leave 56-4 the same and then do the divide part?

would it = 5^10
• Dec 8th 2009, 07:41 AM
craig
Quote:

Originally Posted by andyboy179
what so i leave 56-4 the same and then do the divide part?

would it = 5^10

Yes. When multiply or dividing just remember the two rules above. It doesn't matter what the base numbers are, (5 or 25), as long as they are the same.

Hope this has helped, be sure to post again if there's anything you stuck on ;)
• Dec 8th 2009, 07:46 AM
andyboy179
thankyou so much for all of the help!!!(Rock)