What is the pair of integers when the product is 20 and he sum is 9??

1 Answer
May 10, 2018

4, 5

Explanation:

Let our integers be x and y.

From the question:

xy=20
x+y=9

By rearranging the second equation:

x=9-y

Substitute this into the first equation:

y(9-y)=20
9y-y^2=20
-y^2+9y-200 y^2-9y+20=0 (y-4)(y-5)=0#

y=4 or y=5

Sub these into either of the two equations to find x:

Let y=4

4x=20
x=5

Let y=5
5x=20
x=4

So x=4, y=5 or x=5, y=4

Either way, our two integers are 4 and 5