SOLUTION: Find two positive real numbers with the smallest possible sum whose product is 25

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Question 423764: Find two positive real numbers with the smallest possible sum whose product is 25
Answer by Gogonati(855) About Me  (Show Source):
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Solution: Denote the first real number with x, since their product is 25, than the second number is: 25/x. Our function who gives the smallest possible sum is:
y=+x%2B%2825%2Fx%29 We need to find the minimum value for this function.
y=%28x%5E2%2B25%29%2Fx+ We find the derivative of this function and the value of x, where this derivative is zero. y'= 1-(25/x^2), x^2-25=0.
The real numbers that satisfy our problem are: x%5B1%5D=x%5B2%5D=-5
The graphic solution is given bellow
graph%28400%2C+400%2C+-6%2C+6%2C+-30%2C+2%2C+x%5E2-25%29