What number must you add to complete the square? x2-20x=17a. 100b. -10c.-100d. 10

The number is 100

A is correct

Step-by-step explanation:

Given:

We need to make completing square at left side.

Rule: We add a number " take half of the coefficient of x and then square it"

Coefficient of x = 20

Half of 20 = 10

Square of 10 = 100

So, we will add 100 both sides make completing square.

Now we make completing square to add 100

Add 100 both sides

Now we will factor left side perfect square

is completing square or perfect square.

Hence, The number is 100

hey there : ) your answer would be a.

step-by-step explanation:

the answer is about 24 dollars