kimye21
The length of a rectangle is 7 inches more than the width. The perimeter is 42 inches. Find the length and width
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kimye21
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|dw:1348706471681:dw|
dpflan
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Cool, so for that rectangle, perimeter is 42. How do you find the perimeter?
dpflan
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Do you know the formula for finding the perimeter of an object?
kimye21
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i think its p=2l+2w
dpflan
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yeah, in this case for the rectangle, P = 2*length + 2*width. So you have values for the length and the width, right?
L = x + 7
W = x
dpflan
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Plug those values into the perimeter function, what does the equation look like after doing that?
kimye21
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my equation looks like this
42=2(7)+2w
42-14=28
which makes w = 14
then for L
14+7=21
am i right
dpflan
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Getting there, so the values you have for each dimension are actually variables - (x+7), and x
Therefore P = 2*L + 2*W becomes
L = x + 7
W = x
P = 2*(x+7) + 2*(x)
42 = 2*(x+7) + 2*(x)
dpflan
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Because there is only one variable, one unknown, that being 'x', we can easily then solve for it from the adjusted equation.
dpflan
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Does that make sense? Give that equation a shot, and solve for x.
kimye21
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x=7
dpflan
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Definitely! that's it, so L = ? and W = ?
dpflan
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Just have to do that last step and you're donw
dpflan
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Quite easy after finding x...
kimye21
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so w = 7 and l=14
dpflan
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Nice work
kimye21
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thanks