SOLUTION: How do I solve the following problem? Evaluate C(7,3). Thank you.

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Question 224817: How do I solve the following problem?
Evaluate C(7,3).
Thank you.
Answer by LtAurora(115) About Me  (Show Source):
You can put this solution on YOUR website!
The equation for C is: n%21%2F%28%28n-r%29%21r%21%29.
C is used to find the coefficient in a binomial expansion.
Another way to look at this is that the formula finds the coefficient in the Pascal triangle that corresponds to the %28x%2By%29%5E7 row at the third power. Just a faster way than writing out the Pascal triangle all the time.
This one goes like this:
%287%2A6%2A5%29%2F%283%2A2%2A1%29
The 6 and the 3*2 cancel out to give us:
%287%2A5%29%2F1
Which is 35.