How do you solve using the completing the square method #x^2 +8x = 7#?

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Answer 1 · 2016-03-20T00:16:19

Add #16# to both sides to "complete the square" on the left hand side and hence find:

#x = -4+-sqrt(23)#

One way is as follows:

First add #16# to both sides to get:

#x^2+8x+16 = 23#

Note that #x^2+8x+16 = (x+4)^2#, so we have:

#(x+4)^2 = 23#

Therefore:

#x+4 = +-sqrt(23)#

Hence:

#x = -4+-sqrt(23)#