Question

Write an equation for the following, then solve. Show your work.

If a number is subtracted from its square, the result is 90. Find the number(s).

Answer 1

x = -9, 10

Explanation:

`x^2 - x = 90\\`

Solve this as a quadratic equation, so subtract 90 from both sides:

`x^2-x-90=0`

Factoring:

`(x+9)(x-10) = 0`

This means that:

`x + 9 = 0\\\\x=-9\\or\\x - 10 = 0\\x = 10`

x can be -9 or 10.