How do you solve x^ { 2} + 10x = 15?

1 Answer

x=-5+-2sqrt10

Explanation:

x^2+10x=15
x^2+10x-15=0

Apply factoring (what multiplies to -15 and adds up to 10?)
if no answer, then proceed to quadratic equation

x=(-b+-sqrt(b^2-4ac))/(2a)
x=(-10+-sqrt(10^2-4*1*-15))/(2*1)
x=(-10+-sqrt160)/(2)
x=(-10+-4sqrt10)/(2)
x=-5+-2sqrt10

It's long at first, but after a while, you'll get the hang of it and you can do it in your head