Question

The next term of the A.P. 7, 28, 63, ... is

Answer 1

First term of A.P is 7 that is a

d is 21

an = a + ( n - 1 )d

a4 = 7 + 3 × 21

a4 = 7 + 63

a4 = 70
the next term is 70 ...

Answer 2

Given AP is: √7, √28, √63,.......

                 = √7, 2√7, 3√7,......

Next term = 4th term = a + 3d

                                = √7 + 3*√7    (first term a =√7 and common difference d = 2*√7-√7 = √7)

                                = 4*√7

                                = √(7*4*4)

                                = √112