How do you solve using the completing the square method #x^2+2x-7=17#?

2 Answers
May 14, 2017

Answer:

The solution is #x=4 or x=-6#.

Explanation:

We have:

#x^2+2x-7=17#

Adding 8 to both sides completes the square on the left.

#x^2+2x+1=25#

Completing squares gives:

#(x+1)^2=5^2#

Taking square roots gives:

#x+1=+-5#

This gives:

#x=4 or x=-6#

May 14, 2017

Answer:

#{-6;4}#

Explanation:

#x^2+2x−7=17#

#=> x^2 +2x +1 = 25#
#=> (x+1)^2 = 25#
#=> x+1 = 5# or #x+1 =-5#
#=> x = 4# or #x = -6#