# Math Help - subtracting powers?

1. ## subtracting powers?

How do you subtract powers?

(i) 72 – 62
(ii) 92 – 82

Thanks

2. Originally Posted by Sailee316
How do you subtract powers?

(i) 72 – 62
(ii) 92 – 82

Thanks
These are not powers. Do you mean
$\text{(i)}\;7^2 - 6^2$ and
$\text{(ii)}\;9^2 - 8^2$?

If so, then just evaluate the powers separately and then subtract:
\begin{aligned}
7^2 - 6^2 &= 49 -36 \\
&= 13
\end{aligned}

I'll let you try the other one yourself.

01

3. Originally Posted by yeongil
These are not powers. Do you mean
$\text{(i)}\;7^2 - 6^2$ and
$\text{(ii)}\;9^2 - 8^2$?

If so, then just evaluate the powers separately and then subtract
[snip]
Alternatively, use $a^2 - b^2 = (a - b)(a + b)$.