Find the sum of the first 60 terms of the sequence below a_n=5n+10

 

means that the value of the n'th term of the sequence is 5n+10

for example, the value of the seventh term is  

The sum of the first 60 terms can be calculated as follows:

 





using the Gauss formula for the addition of the first n natural numbers:



thus we have:





 9,750