Find the sum of `1+3+5+…+` to 40 terms

Find the sum of the firt 40 terms of the series 1^(2) -2^(2) + 3^(2) - 4^(2) +……….

Find the sum of the series to n terms and to infinity : (1)/(1.3)+ (1)/(3.5) +(1)/(5.7) +(1)/(7.9)+...

Find the sum of the first 40 terms of the A.P. whose 4th term is 8 and 6th term is 14.

Find the sum of the series upto n terms 1.3.5+3.5.7+5.7.9+....

Find the sum of: 24 terms and n terms of 2 (1)/(2) , 3 (1)/(3) , 4 (1)/(6) ,5 ,......,

If the sum of first 8 terms of an Arithmetic progression is 136 and that of first 15 terms is 465, then find the sum of first 25 terms. OR Ths sum of the 5th and 9th terms of an A.P. is 40 and the sum of the 8th and 14th term is 64. Find the sum of the first 20 terms.

Find the sum of the first 5 terms of the G.P whose first term is 1 and common ration is 2/3.

The first term of a GP is 1 and the sum of its 3rd and 5th terms is 90. Find the common ratio of the GP.

Find the sum of the first n terms of an A.P. 1,4,7,10,…….. Also, find S_(40) .