Math
posted by Maxie on .
The length of a rectangle is 8 cm greater than its width. Find the dimensions of the rectangle if its area is 105 cm.
How do I solve?

Area = Length*Width
Information you are given:
Area = 105cm^2
and
Length = width + 8
therefore:
105 = (width + 8)*width
105 = width^2 + 8*width
105 = w^2 + 8w
rearranging we get a quadratic:
w^2 + 8w  105 = 0
w^2  7w +15w  105 = 0
w(w  7) + 15(w  7) = 0
(w  7)(w + 15) = 0
The two possible solutions are
width = 7 or width = 15
Well, the width must be a positive measurement so we take the width = 7
So the answer is:
Width = 7
Length = 7 + 8 = 15
Ok,
Hope that helps 
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