[" 10.If the first,second and the last terms of "],[" an A.P.are "a,b,c" respectively,then the "],[" sum of the A.P.is "]

If the first second and last terms of an A.P.are a,b and 2a respectively,then its sum is

If the first second and the last terms of an A.P are a,band 2a , respectively, then its sum is

The first, second and last terms of an A.P. are a, b, c respectively, then the sum to first n terms is

If the first,second and last term of an AP are a,b and 2a respectively,its sum is

The first, second and middle terms of an A.P. are a, b, c, respectively. Then the sum of all terms of the A.P. is

If the first, second and last terms of A.P. be a, b, and c respectively, show that the sum of all terms of the A.P. is ((a+c)(b+c-2a))/(2(b-a)) .

First,Second and last terms of a finite A.P.are m,n and 2m respectively,then sum of the series is

If first term, second term and last term of an A.P are a,b and 2a respectively then there sum is……