# How do you solve x^2 + 2x = 8 by completing the square?

Jul 15, 2016

Just take 8 on the other side and get started!

#### Explanation:

Well, as i said take 8 to other side;
${x}^{2} + 2 x - 8 = 0$

Now,
for completing the square method,here are the steps you apply to every quadratic equation mostly:

(1) First multiply the coefficient of ${x}^{2}$ with the term containing no x.
In this case its : (-8*1)=-8

(2) Now break this term in such a way that the sum or difference of those breaked terms give you the coefficient of the term which has x and the multiplication of those terms give you the original term.

In this case its: 4 ans -2 because the multiplication of these two terms gives you 8 (4*-2=-8) and the sum of these two terms gives you the coefficient of the term containing x i.e. 2 (4-2=2).

(3) Now write the equation with those terms, in the form of x.

In this case: ${x}^{2} + 4 x - 2 x - 8 = 0$

(4). Now take common such that the terms inside the bracket are same :
In this case: $x \left(x + 4\right) - 2 \left(x + 4\right) = 0$
which reveals the same equation.

(5). now write the bracket terms in one bracket and combine the terms outside in one bracket.

In this case: $\left(x - 2\right) \left(x + 4\right)$.

Hence the answer is this and thus the roots are 2,-4.
:)