Question

if first term of an ap is a, second term is b and last term is c, then show that the sum of all terms is (a+b)(b+c-a) /2(b-a) ​

Answer 1

Answer:

Last term = a+(n-1)(b-a)=c

n-1=(c-a)/b-a

n=(c-a)/(b-a) +1

=(b+c-2a)/b-a

sum of n terms =n/2(T1+TN)

=(b+c-2a)(a+c)/2(b-a)