Question 77762
To solve for x, we need to use the quadratic formula:

*[invoke quadratic "x", 1, 2, 5]

So our answer is 

{{{x=-1+2i}}} or {{{x=-1-2i}}}

The value of k that completes the square will be equal to the square of half of 10, which looks like this

{{{k=(10/2)^2}}}

{{{k=5^2}}}

{{{k=25}}}


So our polynomial becomes

{{{x^2+10x+25}}}

Notice how it can be factored to {{{(x+5)(x+5)=(x+5)^2}}} which is a perfect square