How do you solve using the completing the square method x^2 + 2x = 35?

1 Answer
Alan P.
Apr 9, 2016

x=5
or
x=-7
(see below for solution by completing the squares)

Explanation:

Given x^2+2x=35

Complete the square:
color(white)("XXX")x^2+2xcolor(red)(+1)=35color(red)(+1)

Re-write as squared terms
color(white)("XXX")(x+1)^2=6^2

Take square root of both sides:
color(white)("XXX")x+1=+-6

x=5 or x=-7

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