How do you solve using the completing the square method x^2 + 2x = 0x2+2x=0?

1 Answer
Mar 22, 2016

Please follow the process given below. Answer is x=0x=0 and x=-2x=2

Explanation:

We know that (x+a)^2=x^2+2ax+a^2(x+a)2=x2+2ax+a2, hence to complete say x^2+bxx2+bx to a square we should add and subtract, square of half the coefficient of xx i.e. (b/2)^2(b2)2.

As the equation is x^2+2x=0x2+2x=0, we have to add and subtract (2/2)^2=1(22)2=1 and equation becomes

x^2+2x+1-1=0x2+2x+11=0 and now this can be written as

(x+1)^2-1=0(x+1)21=0 or

((x+1)+1)xx((x+1)-1)=0((x+1)+1)×((x+1)1)=0 or

((x+2)xx x=0((x+2)×x=0 i.e. either x=0x=0 or x+2=0x+2=0 or x=-2x=2