SOLUTION: The sum of two positive numbers is 9 and the product is a maximum. What are the numbers? Round your answer to one decimal place. Whats the first number?

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Question 628672: The sum of two positive numbers is 9 and the product is a maximum. What are the numbers? Round your answer to one decimal place.
Whats the first number?

Answer by John10(297) About Me  (Show Source):
You can put this solution on YOUR website!
The sum of two positive numbers is 9 and the product is a maximum. What are the numbers? Round your answer to one decimal place.
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Let x and y be positive numbers
x + y = 9
y = 9 - x
Let A be the maximum product of x and y.
A = xy = x(9 - x) = 9x - x^2
Now we will use the vertex formula to find x:
x = -b/2a = -(9)/2(-1) = 9/2 = 4.5
So x is 4.5 then y = 9 - 4.5 = 4.5
So x = y = 4.5
Hope it helps:)
John10