Factorisation - Method of Completing the Square

Factorize each of the following quadratic polynomials by using the method of  completing the square:
p² + 6p + 8

Factorize each of the following quadratic polynomials by using the method of completing the square:
4y² + 12y + 5

Factorize each of the following quadratic polynomials by using the method of completing the square:
p² + 6p − 16

Factorize each of the following quadratic polynomials by using the method of completing the square:
x² + 12x + 20

Factorize each of the following quadratic polynomials by using the method of completing the square:
a² − 14a − 51

Factorize each of the following quadratic polynomials by using the method of completing the square:
a² + 2a − 3