How do you solve #x^2 + 2x = 3# by completing the square?

1 Answer
Jul 15, 2015

Answer:

Add the square of half the coefficient of #x# to both sides; take the square root of both sides and perform standard arithmetic operations to get: #x = -3 or +1#

Explanation:

Given #x^2+2x=3#

Add the square of (#1/2# of #2#)
#color(white)("XXXX")##x^2+2x+1 = 3+1#

Rewrite the left side as a binomial square (and simplify the right side)
#color(white)("XXXX")##(x+1)^2 = 4#

Take the square root of both sides
#color(white)("XXXX")##x+1 = +-2#

Subtract #1# from both sides
#color(white)("XXXX")##x= -3 or +1#