Question

Solve this quadratic equation by completing the square.

Answer 1

Answer:

$x=-3+\sqrt{27}\\ x=-3-\sqrt{27}$

Step-by-step explanation:

Let's find our C value for the quadratic equation.

$(\frac{6}{2})^{2} = 9$

That is our C. Since we added 9 to one side, we have to do the same to the other. We get:

$x^{2} +6x + 9 = 18 + 9\\x^{2} +6x + 9 = 27$

Now, lets form the left side as a binomial squared.

$(x+3)^{2} = 27$

Let's square both sides now:

$x+3 = (+/-)\sqrt{27}$

Now, we subtract 3 from both sides to isolate the variable, X:

$x= -3(+/-)\sqrt{27}$

This means that the answers are:

$x=-3+\sqrt{27}\\ x=-3-\sqrt{27}$

I do not understand your answers though. Answer A makes no sense, answer B is 221, answer C is 115, and answer D also does not make sense. If you could clarify this portion, maybe I can help you find your alphabetic answer