Answer:
=
(
x
+
3
)
(
3
x
−
4
)
Step-by-step explanation:
Use a version of the AC Method.
A
=
3
, B
=5
, C
=
12
Since the sign on the constant term is −
, look for a pair of factors of A
C
=
36 whose difference is B
=
5
The pair 4
, 9 works.
Now use that pair to split the middle term, then factor by grouping:
3
x
2
+
5
x
−
12 =
3
x
−
4
x
+
9
x
−
12
=
(
3
x
2
−
4
x
)
+
(
9
x
−
12
) =
x (
3
x
−
4
)
+
3
(
3
x
−
4
)
