SOLUTION: find the dimensions of a rectangle whose perimeter is 20 meters and whose area is 21 square meters.

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Question 900676: find the dimensions of a rectangle whose perimeter is 20 meters and whose area is 21 square meters.
Answer by josgarithmetic(39617) About Me  (Show Source):
You can put this solution on YOUR website!
2x+2y=20 and xy=21.
Just solve these simultaneous equations as a system.

Perimeter equation simplifies to x+y=10.

y=10-x
-
x%2810-x%29=21
-x%5E2%2B10x-21=0
x%5E2-10x%2B21=0
%28x%2B3%29%28x-7%29=0
The value for x that you must use is highlight%28x=7%29.
y=10-7
highlight%28y=3%29