Question

find the sum of 35 term of an ap whose second term is 2
and 7th term is 22

Answer 1

S25=?
A2=2
A7=22
.... here is your soln
AN =A+(n-1)d
A2=a+d
2=a+d... 1st eqn
A7=a+6d
22=a+6d .. 2nd eqn
subtract 1st and 2nd eqn to get the value of d so , d=4 now find the value of a by substituting d value in eqn 1 ..so a=-2
now use the for s=35/2 ×2a+34d so the ans will be 2376.. i.e the submition ..
..
.. i hope it helps