SOLUTION: What is the largest number you can obtain by multiplying two real numbers whose sum is 9?

Question 543931: What is the largest number you can obtain by multiplying two real numbers whose sum is 9?

Answer by stanbon(75887) (Show Source): You can put this solution on YOUR website!
What is the largest number you can obtain by multiplying two real numbers whose sum is 9?
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Equations:
x + y = 9
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Product = xy = x(9-x)
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P = -x^2+9x
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Max occurs when x = -b/(2a) = -9/(2*-1) = 4.5
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Solve for "y":
y = 9-x = 4.5
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Maximum product = 4.5^2 = 20.25
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Cheers,
Stan H.
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