Question

100 points please help me asap!!

Answer 1

`(x+5)^2=4`

Explanation:

We have:

`x^2+10x+21=0`

First, subtract 21 from both sides:

`x^2+10x=-21`

Now, we can complete the square. We will divide the coefficient of the b term and square it. So:

`((b)/(2))^2\Rightarrow((10)/(2))^2=(5)^2=25`

So, we will add 25 to both sides:

`(x^2+10+25)=-21+25`

The left is the perfect square trinomial pattern. Add on the right:

`((x)^2+2(5)(x)+(5)^2)=4`

Final step:

`(x+5)^2=4`