y⁴ + 12y² + 36
Now factorize the expression
y⁴ + 6y² + 6y² + 36
= y²(y² + 6) + 6(y² + 6)
= (y² + 6) (y² + 6)
Now 6 is not the perfect square and according to rule, binomial can not be factored as the difference of two perfect squares.
so multiply both.
(y² + 6)² is the answer.
