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find two positive real numbers such that the sum of the first number and the second number is 48 and their product is a maximum

1 Answer

2 votes

Answer:

x = 24 and y = 24

Explanation:

Let's use algebra to solve this optimization problem.

Let x be the first number, and y be the second number. Then we have the following two equations based on the problem statement:

x + y = 48 (sum of the two numbers is 48)

xy = ? (product of the two numbers, which we want to maximize)

To solve for x and y in terms of each other, we can use the fact that:

(x + y)^2 = x^2 + 2xy + y^2

Expanding the left side of the equation gives:

x^2 + 2xy + y^2 = 2304

And substituting xy for its value in terms of x and y gives:

x^2 + 2xy + y^2 = x^2 + 2(48 - x)y + y^2 = 2304

Simplifying this equation gives:

2y^2 - 96y + x^2 - 2304 = 0

To maximize the product xy, we need to maximize the value of xy = x(48 - x) = 48x - x^2. This function is a quadratic that opens downwards, and therefore, its maximum value occurs at the vertex of the parabola, which is located at x = -b/2a = -48/(2*-1) = 24.

Thus, the two positive real numbers that sum up to 48 and their product is a maximum are x = 24 and y = 24.

User Bo Frederiksen
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