The value of \[\frac{1}{(1+a)(2+a)}+\frac{1}{(2+a)(3+a)}\] \[\frac{1}{(3+a)(4+a)}\]+ ..... +\[\infty \] is, (where a is a constant) [AMU 2005]

The value of \[\frac{1}{(1+a)(2+a)}+\frac{1}{(2+a)(3+a)}\] \[\frac{1}{

1.	The value of \[\frac{1}{(1+a)(2+a)}+\frac{1}{(2+a)(3+a)}\] \[\frac{1}{(3+a)(4+a)}\]+ ..... +\[\infty \] is, (where a is a constant) [AMU 2005]
A.	\[\frac{1}{1+a}\]
B.	\[\frac{2}{1+a}\]
C.	\[\infty \]
D.	None of these
Answer» B. \[\frac{2}{1+a}\]

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The value of \[\frac{1}{(1+a)(2+a)}+\frac{1}{(2+a)(3+a)}\] \[\frac{1}{(3+a)(4+a)}\]+ ..... +\[\infty \] is, (where a is a constant) [AMU 2005]

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