Question

First term of ap is 2 and sum of the first five terms is 14 the sum of the next fight terms then find the sum of 20th term

Answer 1

Answer:

First term = 2

Let d be the common difference of the A.P.

Therefore, the A.P. is 2, 2 + d, 2 + 2d, 2 + 3d, …

Sum of first five terms = 10 + 10d

Sum of next five terms = 10 + 35d

According to the given condition, =>10+10d = 1/4(10+35d)

=>40+40d = 10+35d

=>30 = −5d

=>d = −6

∴ a20 = a+(20−1)d = 2+(19)(−6) = 2−114 = −112

Hence, the 20th term of the A.P. is –112