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OK, I got a new one... it's $36 m^2 - \frac{25}4 $

and I got:

$(18m-\frac{5}2 )(18m+\frac{5}2 )$ although that is incorrect... where did I go wrong?

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Try taking the square root of $36m^2$ again. – AMPerrine Oct 28 '11 at 21:25
six times six is thirty-six – André Nicolas Oct 28 '11 at 21:31
And $18\times18$ is not 36. – Gerry Myerson Oct 28 '11 at 21:39
up vote 3 down vote accepted

I don't think you are right,since:

$$ 36 m^2 - \frac{25}4 = (6m)^2 - \left(\frac{5}2 \right)^2 = \left(6m + \frac{5}2 \right)\left(6m - \frac{5}2 \right) $$

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Arg... I tried adding instead of multiplying.. thank you. – naknode Oct 28 '11 at 21:43

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