SOLUTION: The width of a rectangle is 2x + 3 and its length is x + 7. If the area is 40 in^2, what are the dimensions of the Rectangle?

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Question 482608: The width of a rectangle is 2x + 3 and its length is x + 7. If the area is 40 in^2, what are the dimensions of the Rectangle?
Answer by ankor@dixie-net.com(22740) About Me  (Show Source):
You can put this solution on YOUR website!
The width of a rectangle is 2x + 3 and its length is x + 7.
If the area is 40 in^2, what are the dimensions of the Rectangle?
:
We know the area = width * length, therefore
(2x+3)*(x+7) = 40
FOIL
2x^2 + 14x + 3x + 21 = 40
2x^2 + 17x + 21 - 40 = 0
2x^2 + 17x - 19 = 0
You can use the quadratic formula, but this will factor to
(x-1)(2x+19) = 0
the positive solution is what we want here
x = 1
therefore
the width: 2(1) + 3 = 5
the length: 1 + 7 = 8
:
Check by finding the area: 5 * 8 = 40