Math Is Fun Forum

  Discussion about math, puzzles, games and fun.   Useful symbols: ÷ × ½ √ ∞ ≠ ≤ ≥ ≈ ⇒ ± ∈ Δ θ ∴ ∑ ∫ • π ƒ -¹ ² ³ °

You are not logged in.

#1 2006-11-20 23:47:58

deesin
Member
Registered: 2006-11-20
Posts: 10

expansion.please help me!

expand,

           r(r+1)(r+2)(r+3).......(r+k) ?


Mathematics is the science which draws necessary conclusions
Mathematics consists of proving the most obvious thing in the least obvious way.

Offline

#2 2006-11-20 23:50:50

mathsyperson
Moderator
Registered: 2005-06-22
Posts: 4,900

Re: expansion.please help me!

That would be absolutely horrible to expand. You'd get a big long polynomial with huge coefficients and it wouldn't look nice at all. Plus, with the number of multiplied terms varying with k, I'm not sure it can even be done.

However, there is a much nicer notation for writing it down.

r*(r+1)*(r+2)*(r+3)*...*(r+k) is equivalent to (r+k)!/(r-1)!.


Why did the vector cross the road?
It wanted to be normal.

Offline

Board footer

Powered by FluxBB