Question

the value of n²+2n[1+2+3+......+(n-1)] is​

Answer 1

Answer:

n²+2n[1+2+3+....+(n-1)]

=n²+2n[n-1(n-1+1)/2]

=n²+n[n-1(n)]

=n²+n[n²-n]

=n²+n³-n²

=n³

I hope this answer may help you dear