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Find two nonegative numbers whose sum is 9 and so that the product of one number and the square of the other number is a maximum

User DragonWork
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Answer:

Explanation:

Let one number = x

Let the other number = y

x + y = 9

xy2 is a maximum

Since we need positive numbers, we assign values of x and y respectively that will give us a sum of 9.

x: 0, 1, 2, 3, 4, 5, 6, 7, 8, 9

y: 9, 8, 7, 6, 5, 4, 3, 2, 1, 0

Next, we square the values of y.

y2: 81, 64, 49, 36, 25, 16, 9, 4, 1, 0

Next, we multiply x by y2 to see which product is the highest value.

x : 0 , 1 , 2 , 3 , 4 , 5 , 6, 7, 8, 9

y2 : 81, 64, 49, 36, 25, 16, 9, 4, 1, 0

We can eliminate x = 0, x = 8 , and x = 9 , since the product of xy2 is of lowest value.

1 x 64 = 64

2 x 49 = 92

3 x 36 = 108

4 x 25 = 100

5 x 16 = 80

6 x 9 = 54

7 x 4 = 28

The highest product value here is 108.

The two numbers in the solution are 3 and 6.

User Haraldmartin
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