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Math Help - subtracting powers?

  1. #1
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    subtracting powers?

    How do you subtract powers?

    (i) 72 62
    (ii) 92 82

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  2. #2
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    Quote Originally Posted by Sailee316 View Post
    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}<br />
7^2 - 6^2 &= 49 -36 \\<br />
&= 13<br />
\end{aligned}

    I'll let you try the other one yourself.


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  3. #3
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    Quote Originally Posted by yeongil View Post
    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).
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