Problem with series

[enthumath]

Hi

I'm having trouble finding the sum of:

1 x 2 + 2 x 3 + 3 x 4 + 4 x 5...........1994 x 1995

Any help would be excellent

Thanks

[zaza]

Each term is some integer x multiplied by the next one up, i.e. x+1.

Write this in terms of a summation, expand out of the brackets and then separate the two series, and you'll find that they are standard.

zaza

[enthumath]

Zaza,

I still can't find a solution

I expanded as follows:

x(x + 1) + (x + 1)(x +2) + (x +2)(x + 3)...............

i still get constants which are still 2 + 6 + 12 + 20 .........

[zaza]

Write it in terms of a summation.


i.e. use the Σ notation.

[tendemo]

Something like ∑ (x² + x) ? Can be continued from there.