Question

the sum of first 5 terms of an AP is 100 and sum of first 10 terms of an AP is 350.Find the third term.​

Answer 1

Answer:

T3 = 30

Step-by-step explanation:

The given is

S10 = 350 = n/2*[2a + (n-1)*d]

350 = 10/2 *[2a + (10-1)d]

350 = 5[2a + 9d]

350/2 = 2a + 9d

70 = 2a + 9d ...........(1)

also it is given that

S5 = 100 = 5/2 [2a + (5-1)*d]

100*2/5 = 2a + 4d

40 = 2a + 4d ............(2)

so from equation (1) and (2)

we get the value of a and d

a = 6

d = 7