How do you solve the equation x^2+2x-6=0 by completing the square?
1 Answer
Dec 24, 2016
Explanation:
The difference of squares identity can be written:
a^2-b^2 = (a-b)(a+b)
Use this with
0 = x^2+2x-6
color(white)(0) = x^2+2x+1-7
color(white)(0) = (x+1)^2-(sqrt(7))^2
color(white)(0) = ((x+1)-sqrt(7))((x+1)+sqrt(7))
color(white)(0) = (x+1-sqrt(7))(x+1+sqrt(7))
Hence:
x = -1+-sqrt(7)
