Question

Which term of the A.P.4,7,10,...is 64?

Answer 1

Answer:

64 = a + (n-1)d

==> 64 = 4 + (n-1) 3

==> 60 = (n-1)3

==> 20 = n-1

===> n = 21

Answer 2

4,7,10,...is 64?

a=4

d=a₂-a₁,d=3

taking formula

aₙ=a+(n-1)d

64=4+(n-1)3

64-4=(n-1)3

60=(n-1)3

60/3=(n-1)

20=n-1

20+1=n

n=21