What two number adds up to -2 but multiply to -8

Mathematics · High School · Mon Jan 18 2021

llm

Answered on Thu Jul 14 2022

Let the first number be x

And, 2nd number be y

Then, according to question

xy = -8 …1

x + y = -2 …2

From equation 2,

y = -2 - x

Putting value of y in equation 1, we get

x(-2 - x) = -8

-x² - 2x = -8

x² + 2x -8 = 0

By middle-term split method

x² + 4x - 2x -8 = 0

x(x + 4) -2(x + 4) = 0

(x + 4) (x -2) = 0

So, x = -4 and x = 2

Now, value of y when x = -4

y = -8/-4

y = 2

And, value if y when x = 2

y = -8/2

y = -4