Practice Exercise 95 Further problems on the binomial series In Problems 1 to 5 expand in ascending powers of x as far as the term in x3,using the binomial theorem. State in each case the limits of x for which the series is valid.
1.
1/ (1−x)
2.
1/ (1+x)2
3.
1/ (2+x)3 

4. √2+x
5.
1/ √1+3x