Answer:
(3x + y)(3x - 4)
Explanation:
9x² + 3xy - 12x - 4y =
There is no common factor in the 4 terms.
Since there are 4 terms, we try factoring by grouping.
Find a common factor in the first two terms, and find a common factor in the last two terms.
= 3x(3x + y) - 4(3x + y)
Now factor out the common factor 3x + y.
= (3x + y)(3x - 4)