I need help with the following question:

A playground, which measures 60m by 40m, is to be doubled in area by extending each side of the playground by an equal amount. Determine how much eash side should be extended.

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- Nov 18th 2007, 11:52 AMsadaf_rehmanQuadratics Formula
I need help with the following question:

A playground, which measures 60m by 40m, is to be doubled in area by extending each side of the playground by an equal amount. Determine how much eash side should be extended. - Nov 18th 2007, 11:58 AMJhevon
the original area is 60*40 = 2400 cubic meters

Let the length each side is extended by be $\displaystyle x$.

Thus the new area is given by:

$\displaystyle A = (60 + x)(40 + x)$

we are told that with this extension, the area is doubled. thus we have,

$\displaystyle (60 + x)(40 + x) = 4800$

now solve for $\displaystyle x$ to find the extension - Nov 18th 2007, 12:19 PMsadaf_rehman
how do i solve for x?

- Nov 18th 2007, 12:45 PMJhevon
do you know how to expand brackets? take each term in one set of brackets and multiply each term in the other set

$\displaystyle (60 + x)(40 + x) = 4800$

$\displaystyle \Rightarrow 2400 + 60x + 40x + x^2 = 4800$

$\displaystyle \Rightarrow x^2 + 100x - 2400 = 0$

this is a quadratic equation, can you continue?