# exponents

• April 28th 2008, 01:49 PM
nugiboy
exponents
Basicly, ive got the following:

8^2.5 times 2^-0.5

On the mark scheme, it changes the 8^2.5 to 2^7.5

I don't understand how it does this step. Can anyone explain?
• April 28th 2008, 01:51 PM
Moo
Hello,

Quote:

Originally Posted by nugiboy
Basicly, ive got the following:

$8^[2.5] * 2^[-0.5]$

On the mark scheme, it changes the $8^[2.5]$ to $2^[7.5]$

I don't understand how it does this step. Can anyone explain?

$8=2^3$

And you know that $(a^b)^c=a^{bc}$

Plus, $a^b a^c=a^{b+c}$

This is all you need for getting from one formula to another.
• April 28th 2008, 01:53 PM
icemanfan
Quote:

Originally Posted by nugiboy
Basicly, ive got the following:

$8^[2.5] * 2^[-0.5]$

On the mark scheme, it changes the $8^[2.5]$ to $2^[7.5]$

I don't understand how it does this step. Can anyone explain?

$8^{2.5} = (2^3)^{2.5} = 2^{3\cdot{2.5}} = 2^{7.5}$

It's just rules of exponents.