SOLUTION: The perimeter of a rectangle is 18 feet, and the area of the rectangle is 20 square feet. What is the length of the rectangle?

Question 242129: The perimeter of a rectangle is 18 feet, and the area of the rectangle is 20 square feet. What is the length of the rectangle?
Answer by checkley77(12844) (Show Source): You can put this solution on YOUR website!
xy=20
x=20/y
2x+2y=18 replace x with (20/y) & solve for y.
2(20/y)+2y=18
40/y+2y=18
(40+2y*y)/y=18
40+2y^2=18y
2y^2+40=18y
2y^2-18y+40=0
2(y^2-9y+20)=0
(y-5)(y-4)=0
y-5=0
y=5 ans.
y-4=0
y=4 ans
x=20/5=4 ans
x=20/4=5 ans.
Proof:
4*5=20
2*4+2*5=18
8+10=18
18=18

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