Question

I don't how I would do this exactly..

What conjecture can you make about the sum of the first 10 positive even numbers?

2 = 2 = 1 times 2
2 + 4 = 6 = 2 times 3
2 + 4 + 6 = 12 = 3 times 4
2 + 4 + 6 + 8 = 20 = 4 times 5
2 + 4 + 6 + 8 + 10 = 30 = 5 times 6

Choices:

o The sum is 9 times 10
o The sum is 10 times 10
o The sum is 11 time 12
o The sum is 10 times 11

Answer 1

10 times 11. for the first (1) even number you have (1) times (1)+1
for the second(2) you have (2) times (2) + 1. so for the tenth (10) you should get (10) times (10) + 1 ?

Answer 2

so for the sum of the nth even number you have sum = n times (n+1) ?

Answer 3

I kind of understand.

Answer 4

Can you show me an example please?

Answer 5

yeah so for the sum of the 3rd even number, sum = n times (n +1) = 3 times 4 = 12 just like you got

Answer 6

So, n is the first number after the sum = part.

Answer 7

They don't have the first 10 positive even numbers right? They want me to get up to that point.

Answer 8

I understand now. Thank you.