SOLUTION: the length of a rectangle plus its width is 30 cm. the area is 221 square cm. how long is the longest side of the rectangle?

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Question 33274: the length of a rectangle plus its width is 30 cm. the area is 221 square cm. how long is the longest side of the rectangle?
Answer by sarah_adam(201) About Me  (Show Source):
You can put this solution on YOUR website!
Let length of rectangle be L and width be W
given:
L+W = 30cm which implies W = 30-L
Area = 221 cm
but Area = L*W
L*W = 30
L(30-L) = 221
30L - L%5E2 = 221
L%5E2-30L +221 = 0
L%5E2-17L-13L+221 = 0
L(L-17)-13(L-17)=0
(L - 13)(L-17)= 0
L = 13 or L = 17
which gives us W = 17 or W = 13
But we are asked to find our the longest side of the rectangle
so The longest side is 17cm