Question

An integer 2 less than 4 times another. If the product of the two integers is 90 then find the integers

Answer 1

Let x and y be the 2 integers.

Then x = 4y - 2

and xy = 90

Substitute for x in the second equation:-

(4y - 2)y = 90

4y^2 - 2y - 90 = 0

2y^2 - y - 45 = 0

(2y + 9)(y - 5) = 0

so y = 5 ( as it is an integer)

and x = = 90/5 = 18

Answer:- The 2 integers are 5 and 18.