Question

The eight term of an arithmetic progression is -10 and the sum is -350 . Find the first term and common difference .

Answer 1

Answer:

Sum of 1st seven terms

15=25(2a+(5−1)d)3=a+24d3=a+2d−(i)

Sum of 1st 3 terms=3

So,3a+3d=−3 [Considering 1st term as a,a+d,a+2d]

a+d=−1−(ii)

Solving (i) & (ii)

d=3−(−1)d=4

Putting value of d in (ii)

a+4=−1a=−5

So first term=−5 and difference =4