1
2
⋅
Δ
x
⋅
(
y
0
+
y
1
)
+
1
2
⋅
Δ
x
⋅
(
y
1
+
y
2
)
+
1
2
⋅
Δ
x
⋅
(
y
2
+
y
3
)
+
...
+
1
2
⋅
Δ
x
⋅
(
y
n
-1
+
y
n
)