How do you solve #x^2+8x+18 = 0# by completing the square?

1 Answer
Jun 4, 2016

No Solution

Explanation:

To complete the square, we need the perfect square of the equation of #x^2+8x+18# In order to find the perfect square, we need to change the equation into #(x-b)^2=a#, were a and b are constants. To find c, we divide the coefficient by 2 and square it

#(8/2)^2=16#

We get 16, which means that we must change our current equation to have a 16.

#x^2+8x+18-2=-2#

By subtracting 2 from both sides, we get that 16. Now, we can simplify the left hand side into the perfect square

#x^2+8x+16=(x+4)^2#

This means #(x+4)^2=-2#

We now square root both side, giving us #x+4=sqrt-2#

They can never be a negative square root, so therefore there is no answer.