Odd numbers take the form
, where
is an integer. When
, the last odd number would be 799. So we're adding

By reversing the order of terms, we have

and we can pair up terms in both sums at the same position to write

so that we are basically adding 400 copies of 800, and from there we can find the value of the sum right away:

###
We could also make use of the formulas,


We have

Answer:
Its the one on the left
Step-by-step explanation:
Answer:
Can you explain to me what x is?
1.D
2.D
3.C
4.C
5.D
6.2160
7.288
You really shouldn't be waiting untill 1 AM to do your homework!
Take 156, divide by 13 and the multiply by 12. It is 144