`a+(a+d)+(a+ 2d)+....+[a+ (n-1)d]=n/2(2a + (n-1)d)`

Statement-1: The sum of n terms of the series a+(a+d)+(a+2d)+...(a+(n-1)d)=(n)/(2)[2n+(n-1)d] Statement-2:- Mathematical induction is valid only for natural numbers.

Prove that a+(a+d)+(a+2d)+........n "terms"=n/2(2a+(n-1)d)

For all ninNN , prove by principle of mathematical induction that, a+(a+d)+(a+2d)+ . . . to n terms =(n)/(2)[2a+(n-1)d] .

The sum of first n terms of an A.P. S_n = …..A) n/2 [ t_1 + t_n] B) n/2 [a+(n-1)d] C) n/2 [2 + (n-1)d] D)none of these

(ii) sum of series of form (1)/(a(a+d))+(1)/((a+d)(a+2d))+(1)/((a+2d)(a+3d))+......(1)/((a+(n-2)d)(a+(n-1)d))

Show that Lt_(ntooo)[1/(a(a+d))+1/((a+d)(a+2d))+...+1/([a+(n-1)d][a+nd])]=1/(a.d) where a and d are constants. Hence find Lt_(ntooo)[1/1.4+1/4.7+...+1/((3n-1)(3n+2))]

The mean deviation of the series a , a+d , a+2d ,.....,a+2n from its mean is (a) ((n+1)d)/(2n+1) (b) (n d)/(2n+1) (c) (n(n+1)d)/(2n+1) (d) ((2n+1)d)/(n(n+1))

The mean deviation of the series a , a+d , a+2d , , a+2n from its mean is ((n+1)d)/(2n+1) (b) (n d)/(2n+1) (c) (n(n+1)d)/(2n+1) (d) ((2n+1)d)/(n(n+1))