3
x
2
−
3
x
−
60
=
0
Step-by-step explanation:
A quadratic equation whose roots are
α
and
β
and leading coefficient is
a
is
a
(
x
−
α
)
(
x
−
β
)
=
0
Hence, the quadratic equation whose roots are
5
and
−
4
and leading coefficient is
3
is
3
(
x
−
5
)
(
x
−
(
−
4
)
)
=
0
or
3
(
x
−
5
)
(
x
+
4
)
=
0
or
3
(
x
2
−
5
x
+
4
x
−
20
)
=
0
or
3
(
x
2
−
x
−
20
)
=
0
or
3
x
2
−
3
x
−
60
=
0