Question

An integer is 18 more than 4 times another. If the product of the two integers is -18, then find the integers.

Answer 1

Explanation:

x = 4y+18

xy = -18

x = -18/y

-18/y = 4y+18

4y² + 18y + 18 = 0

2y² + 9y + 9 = 0

y = [-9 ±√(9²-4(2)(9))]/[2(2)] = [-9 ± 3]/4 = -1.5, -3

-1.5 is an extraneous solution, so y = -3

x = 6