is 75, then its \[{{20}^{th}}\] terms will be [RPET 1989]
A) 78
B) 79
C) 80
D) 81
Correct Answer: B
Solution :
\[{{T}_{9}}=a+8d=35\] and \[{{T}_{19}}=a+18d=75\] Solving the equations, we get \[d=4\] and \[a=3\] Hence \[{{20}^{th}}\] term of A.P. \[a+19d=3+19\times 4=79\].
You need to login to perform this action.
You will be redirected in
3 sec
