Question

Which term of the A.P. 3, 12, 21, 30,…. will be 90 more than its 50th term ?

Answer 1

a = 3

d = 9

Let the required term be n

=> Tn = T50 + 90

=> Tn = a + 49d + 90

=> Tn = 3 + 49×9 + 90

=> Tn = 3 + 441+ 90

=> Tn = 534

=> a + (n-1) d = 534

=> 3 + (n-1) 9 = 534

=> (n-1) 9 = 531

=> n - 1 = 59

=> n = 60

So,

60th term of the given AP is 90 more than the 50th term

Answer 2

HELLO DEAR,

A.P. 3, 12, 21, 30,….

a = 3 ,d = 9

a50 = [ 3 + (50-1)9]

==> (3 + 441)

==> 444

now ,

an = 444 + 90

==> [3 +(n-1)9] = 534

==> 9n -6 = 534

==> 9n = 540

==> n = 540/9

==> n = 60

I HOPE ITS HELP YOU DEAR,
THANKS