SOLUTION: find two real numbers (x) and (y) such that 2x+y=80 and A=xy is maximum

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Question 1081031: find two real numbers (x) and (y) such that 2x+y=80 and A=xy is maximum
Answer by Boreal(15235) About Me  (Show Source):
You can put this solution on YOUR website!
y=80-2x
substitute
A=x(80-2x)=80x-2x^2
derivative is 80-4x
set that equal to 0 and 80=4x
x=20
y=40
That adds to 80 and the product is 800.
Try x=19 and y=42, product is 798
try x=21 and y=38, product is 798
graph%28300%2C300%2C-10%2C30%2C-50%2C850%2C-2x%2B80%2C80x-2x%5E2%29