(
a
2
−b
2
2ab
+
2(a+b)
a−b
)∗
a+b
2a
+
b−a
b
=
=(
2(a
2
−b
2
)
4ab+(a−b)
2
)∗
a+b
2a
+
b−a
b
=
=(
2(a
2
−b
2
)
4ab+a
2
−2ab+b
2
)∗
a+b
2a
+
b−a
b
=
=(
2(a
2
−b
2
)
(a+b)
2
)∗
a+b
2a
+
b−a
b
=
=
2(a−b)
a+b
∗
a+b
2a
+
b−a
b
=
a−b
a
+
b−a
b
=
a−b
a−b
=1