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

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