Which number completes the square? x2 − 20x +

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! :)

Set up a system of equations

The number is 80 because every number is multiplied by 2