1.

If 'n' is a positive integer, then n.1+ (n-1) . 2+ (n-2). 3+….. + 1.n=

Answer»

`(N (n+1) )/(2)`
`(n (n+1) (n+2) )/( 6)`
`( (n+1)(n+2))/( 2)`
`(n(n+1) (2n+1))/(6)`

ANSWER :B


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