completing the square basic

What do you do to the b value to correctly complete the square?

What value of c would make this a perfect square trinomial?
x² +8x + c
Options: 4, 16, 64, -16

What value of c would make this a perfect square trinomial?
x² - 12x + c

Complete the square for x² + 12x + ____ (find the missing number in the blank)

Complete the square for x² - 14x + ____ (find the missing value that goes in the blank)

Complete the square for x² + 6x + ____ (find the missing value that goes in the blank)

Factor the perfect square trinomial
x² + 14x + 49

Factor the perfect square trinomial: x² + 16x + 64

Factor: x² - 4x + 4

What number is added to BOTH sides to complete the square before solving? x² + 4x + ____ =7 + _____