Which expression is equivalent to
 
											 
											 
											 
											 
											 
											 
											 
											 
											 
											Answer:
The second expression
Step-by-step explanation:
[tex]\sum_{n=3}^{20}{n(n+1)}=\sum_{n=3}^{20}{(n^2+n)}=\sum_{n=3}^{20}n^2+\sum_{n=3}^{20}n[/tex]
You can split up sums.