Question

Evaluate

Answer 1

\[\sum_{n=1 }^{8}n\]
\[\sum n=\frac{ n \left( n+1 \right) }{ 2 }\]
use the formula and plug the value of n

Answer 2

no substitute n=8

Answer 3

\[\sum_{n=1}^{8}n=1+2+3+4+5+6+7+8=36\]
\[or \sum_{n=1}^{8}n=\frac{ 8\left( 8+1 \right) }{2 }=4*9=36\]