Hi does anyone know how to factorise 80 - (5k)^2 thanks in advance.
Last edited by mr fantastic; Nov 16th 2009 at 02:45 AM.
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Originally Posted by birky Hi does anyone know how to factorise 80 - (5k)^2 thanks in advance. You have $\displaystyle (\sqrt{80})^2 - (5k)^2$ so use the Difference of Two Squares formula $\displaystyle A^2 - B^2 = (A - B)(A + B)$.
Hello $\displaystyle 80-(5k)^{2}=80-25k^{2}=-5(5k^2-16)$
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