2
4
6
−2
−4
−6
5
10
15
−5
−10
−15
−20
0,0
–
o
+
←
↓
↑
→
Cubic
f
(
x
)
=
a
x
3
+
b
x
2
+
c
x
+
d
a = 1
b = -1
c = 0
d = 0
f
(
x
)
=
x
3
−
x
2
tangent
gradient = 6.91178
2
4
6
−2
−4
−6
5
10
−5
−10
−15
0,0
Gradient function
f
′
(
x
)
=
3
x
2
−
2
x