Question

Which term of the sequence 2,4,6,8,16,...is 512

Answer 1

nth term=a+(n-1)d
d=2
a=2
nth term=512
512=2+(n-1)2
512-2=(n-1)2
510=(n-1)2
255=(n-1)
n=256

512 is 256th term of AP

Answer 2

a= 2,d=2 ,an=512
an=a+(n-1)d
512=2+(n-1)2
512-2=(n-1)2
510=(n-1)2
510/2=(n-1)
255=n-1
255+1=n
n=256

hence, 256th term of the AP is 512