Question

1+(1+1)+(1+1+1)+......+(1+1.....upto n-1 times)​

Answer 1

Step-by-step explanation:

Required summation is

1+2+3+4+.....(n-1), which is given by

$\frac{n}{2} \times (n + 1)$

Here we need summation till n-1

hence the answer is

$\frac{(n - 1)}{2} \times n$