Factorize each of the following quadratic polynomials by using the method of completing;
y2 – 7y + 12
Coefficient of y2 = 1
Therefore, we have
y2 – 7y + 12 = y2 – 7y + ()2 – ()2 + 12 [By adding and subtracting ()2]
= (y - )2 – ()2 (Completing the square)
= (y - - ) (y - + )
= (y – 4) (y – 3)