2
2
(
) (
)
px
qx
r
x
a
x
b
+
+
−
−
=
2
A
B
C
(
)
x
a
x
b
x
a
+
+
−
−
−
5 2
2
(
) (
)
px
qx
r
x
a
x
bx
c
+
+
−
+
+
=
2
A
B + C
x
x
a
x
bx
c
+
−
+
+
where x2 + bx + c can not be factorised further � Integration by substitution
A change in the variable of integration often reduces an integral to one of the
fundamental integrals The method in which we change the variable to some
other variable is called the method of substitution