Let's apply the following formula:
(x + a)^2 = x^2 + 2ax + a^2
We know that 2ax = -20x
Now, let's solve for a
First, let's divide both sides by 2.
ax = -10x
Now, let's divide both sides by x
a = -10
Now, let's square that value to find the number that completes the square.
a^2 = (-10)^2
a^2 = 100
The number that completes the square is 100.
Have an awesome day! :)
