Question

Find two positive numbers whose difference is 28 and whose product is 2720.

Answer 1

68 and 40

Explanation:

x - y = 28

x * y = 2720

x = 28 + y

(28+y)y = 2720

28y+y^2 = 2720

y^2 + 28y - 2720 = 0

discriminant = 28^2 - 4(-2720) = 784 + 10 880 = 11 644

we are searching only the positive value

y = (-28 + 108)/2 = 80/2 = 40

x = 28 + 40 = 68