Negative numbers

mthmn:

What two numbers add to -20 and when multiplied equal -100?

-25 and 5

mthmn wrote:What two numbers add to -20 and when multiplied equal -100?

Let the 2 numbers be x and y

x+y=-20

xy=-100 => y= -100/x Substitute this back into the first equation

x + -100/x = -20

multiply both sides by x

x^2 - 100 = -20x

now take it all to one side and sovle it as a quadratic equation.