3.1 Pull out like factors :
-3x3y7 + x3y - 6y = -y • (3x3y6 - x3 + 6)
3.2 Factoring 3x3y6 - x3 + 6
Try to factor this multi-variable trinomial using trial and error
Factorization fails
4.1 A product of several terms equals zero.
When a product of two or more terms equals zero, then at least one of the terms must be zero.
We shall now solve each term = 0 separately
In other words, we are going to solve as many equations as there are terms in the product
Any solution of term = 0 solves product = 0 as well.
4.2 Solve : -y = 0
Multiply both sides of the equation by (-1) : y = 0