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

the answer is a

step-by-step explanation: