If the first, second and last terms of an arithmetic series are a,b and c respectively , then the number of terms is

If the first second and last terms of an A.P.are a,b and 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

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 the last terms of an A.P. are a,b,c respectively, then the sum of the A.P. is

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