Question

Find two positive numbers whose product is 64 and whose sum is a minimum. (If both values are the same number, enter it into both blanks.) slader

Answer 1

X = 8, y = 8

Explanation:

This question is an optimization problem. Two equations are going to be needed here

n = x+y

P = xy

Such that 64 = xy

When we divide through by x we get:

y = 64/x

So that n becomes:

n = x + 64/x

n = x+64x^-1

We take derivative

n' = 1-64x^-2

When n' = 0 then a min|max occurs

0 = 1-64x^-2

Such that:

64/x² = 1

Divide through by x²

64 = x²

x = √64

x = 8

Remember y = 64/x

So,

Y = 64/8

Y = 8.

X = 8, y = 8

Thank you!