SOLUTION: The length of a rectangular sign is 3feet longer than the width. If the sign has a area of 40 square feet for advertising , find its length and its width.

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Question 128350: The length of a rectangular sign is 3feet longer than the width. If the sign has a area of 40 square feet for advertising , find its length and its width.
Answer by chitra(359) About Me  (Show Source):
You can put this solution on YOUR website!
Let "x" ft be the width of the rectangle

So lenght will be "3 + x" ft

Given area = 40 ft^2


We know that the area of the rectangle is given by lenght times breadth


40 = x * (x + 3)


40 = x^2 + 3x


==> x^2 + 3x - 40 = 0

==> by the method of factoring we find


==> x^2 + 8x - 5x - 40 = 0


==> x(x + 8) - 5(x + 8) = 0

==> x = 5 Or x = -8

We dont consider the negative values of x.

Therfore x = 5 ft will be the width

and x + 3 = 5 + 3 = 8ft will be the lenght of the rectangle


thus the solution