If using the method of completing the square to solve the quadratic equation x^2+20x+28=0x which number would have to be added to "complete the square"?

100 will have to be added to both sides to complete the square

Step-by-step explanation:

Given:

x^2+20x+28=0

x² + 20x + 28 = 0

x² + 20x = -28

Using completing the square method of solving quadratic equation

Find the square of half of the coefficient of x

Coefficient of x = 20

Half of the coefficient of x = 20/2

= 10

Square of the half of the coefficient of x = 10²

= 100

Add the square of the half of the coefficient of x to both sides of the equation

x² + 20x = -28

x² + 20x + 100 = -28 + 100

(x + 10)² = 72

to plot points   for x just start at the origin (middle) and go to the left however many times it say(if the number is a positive) if the number is a negative then go right however many times it says if it is 0 go nowhere

now keep you pencil there and go up however many times it says on y(if it is positive) if it is negative then go down however many times it says. if it says 0 go nowhere.

you have just plotted a point! now when you finish plotting all of them connect them with a ruler

plot each point as (-3, 7), (0,4), (3,1), (8,-4)   in the parenthesis on the left of the comma is x and the right is y.