Question

One number exceeds another number by 18. Find the numbers if the result of adding their sum and their product is a minimum.

Answer 1

8

Explanation:

The number is a, another number is b.

a = b + 18 So, b=a - 18

(a+b) + ab

= a + a - 18 + a (a - 18)

= 2a - 18 + a^2 - 18a

{ ax^2 + bx + c }

= a^2 -1 6a - 18 {a = 1b = -16 }

When a = b/-2a = -16/-2*1 = 8

the a^2 - 1ba - 18 is minimum,

So the number is 8