Problema Solution
Find two positive integers whose product is 240 and whose difference is 8.
Answer provided by our tutors
Let x = the first positive integer
y = the second positive integer
Equations:
xy=240
x - y = 8
Solution (use the substitution method in solving two equations in two variables):
x - y = 8
x = y+8
xy = 240
(y+8)y=240
y2 + 8y = 240
y2 + 8y - 240 = 0
(y-12)(y+20)=0
y - 12 = 0 and y + 20 = 0
y = 12 and y = -20
But since we're looking for positive integers only, the answer is 12 only. Substitute this to the other equation.
y = 12
xy = 240
x(12)=240
12x=240
x = 240/12
x = 20
The two positive integers are 12 and 20.