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

1 Answer
Radioactive Teddybear
Jun 4, 2017

#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

Related questions
Impact of this question
1036 views around the world
You can reuse this answer
Creative Commons License