Question 8 - A-Level Maths

Exam Board	CAIE
Module	P3 (Pure Mathematics 3)
Year	2010
Session	June
Topic	Integration with Partial Fractions

Express $\frac { 2 } { ( x + 1 ) ( x + 3 ) }$ in partial fractions.
Using your answer to part (i), show that $$\left( \frac { 2 } { ( x + 1 ) ( x + 3 ) } \right) ^ { 2 } \equiv \frac { 1 } { ( x + 1 ) ^ { 2 } } - \frac { 1 } { x + 1 } + \frac { 1 } { x + 3 } + \frac { 1 } { ( x + 3 ) ^ { 2 } }$$
Hence show that $\int _ { 0 } ^ { 1 } \frac { 4 } { ( x + 1 ) ^ { 2 } ( x + 3 ) ^ { 2 } } \mathrm {~d} x = \frac { 7 } { 12 } - \ln \frac { 3 } { 2 }$.