SOLUTION: Solve each problem and show the solutions. 1.find the sum of the first 20 integers 2.find the sum of the first 30 even integers 3.find the sum of the integers from 4 to 128

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Question 1184291: Solve each problem and show the solutions.
1.find the sum of the first 20 integers
2.find the sum of the first 30 even integers
3.find the sum of the integers from 4 to 128
Found 2 solutions by Boreal, ikleyn:
Answer by Boreal(15235)   (Show Source):
You can put this solution on YOUR website!
1. This is n(n+1)/2=20*21/2=210
2. This is n(n+1)=30*31=930
3. sum from 4 to 128
Sum of first 128 is 128*129/2=8256
sum of first 3 is 6
the difference is the answer, or 8250.

Answer by ikleyn(52788)   (Show Source):
You can put this solution on YOUR website!
.

For your info:

            In Math, there is no such a notion as " first 20 integers "     < < < - - - = = =   because it MAKES no SENSE.

            There is a notion " first 20 positive integers ", INSTEAD, if it is what you mean, in reality.