Question

which term of A.P.5,7,911..........is 43?

Answer 1

a=5,d = 2 tn =43

ATQ,

TN/AN=a+ (N-1)d

=> 43 = 5 + (n-1)2

=> 43=5+2n-2

=> 43-3 =2n

=> 40=2n

=> n=40/2

n= 20