Question

If Σn = 10 , then Σn³ = ?

a) 10 b) 25 c) 1000 d) 100 .

Answer 1

We know that,.

 Σn = n(n+1)/2

 Σn³= n²(n+1)²/4 = [ n(n+1)/2]² =(  Σn) ²

So, Given

 Σn = 10

Now,  Σn³ = ( Σn) ² = (10)² = 100 .

Required option is Option D

Hope helped!

Answer 2

answer is c 1000 only ....