The product of two whole numbers is 364. If the difference of the numbers is 15, what is their sum?

Sagot :

Lets Represent:
x-first whole number
y-second whole number

So the product of two whole numbers is 364
xy=364

The difference of the numbers is 15
x-y=15

To solve this problem, we must use substitution, you could pick any equation but i prefer the first one:
xy=364
Divide both sides by y
x=[tex]\frac{364}{y}[/tex]

Now substitute to the second equation

[tex]\frac{364}{y}-y=15[/tex]
Multiply both sides by y to eliminate the denominator
364-y²=15y
Rearrange the equation to Ax²+Bx=C
y²+15y-364=0
Use factoring
(y+28)(y-13)=0
y=-28; y=13

You can find x by using either of the 2 y values
x-y=15
x-(-28)=15
x+28=15
x=-13

x-y=15
x-13=15
x=28

To find the sum:
x+y
(-13+28)=15
or
(28-13)=15