12 items are filed under this topic.
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n choose r equals n-1 choose r plus n-1 choose r - 1 |
2008-07-14 |
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From fae: Prove that
( n ) = ( n – 1) + ( n - 1 )
( r ) ( r ) (r-1)
NOTE: the ( ) should be one for n taken r and so on. but there is no one big ( ) that will cater two lines Answered by Janice Cotcher. |
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Prove that 2nCn is less than 4n, for all positive integers n? |
2006-10-01 |
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From Anna: How can I prove that 2nCn is less than 4n, for all positive integers n? Answered by Penny Nom. |
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What are the 3rd and 4th terms of (2x-y)^7? |
2006-06-18 |
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From April: What are the 3rd and 4th terms of this sequence: (2x-y)7?
I'm having an issue with this...is there any easier way to get it without completely factoring the whoooole thing out? Answered by Penny Nom. |
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Successive coefficients in Pascal's Triangle |
2002-12-27 |
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From Quincy: There is a formula connecting any (k+1) successive coefficients in the nth row of the Pascal Triangle with a coefficient in the (n+k)th row. Find this formula Answered by Penny Nom and Walter Whiteley. |
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Successive coefficients in the nth row of Pascal's Triangle |
2002-06-10 |
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From Tim: There is a formula connecting any (k+1) successive coefficients in the nth row of Pascal's Triangle with a coefficient in the (n+k)th row. find this formula. Answered by Penny Nom. |
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Pascal's Triangle |
2002-04-02 |
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From Brian: It's about (a+b)x. I remember there a triangle with numbers to remember for a faster solution. Can you please teach me? Answered by Penny Nom. |
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Lucas' theorem |
2001-10-09 |
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From Tania: How could I demonstrate: nCp is congruent to floor(n/p) (modulo p)? where rCk is a binomial coefficient, rCk = r(r-1)...(r-k+1)/k(k-1)...1, and p is a prime number Answered by Richard McIntosh. |
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A dollar, quarter, dime, nickle and penny |
2001-01-07 |
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From Sarah: Arnold has a dollar coin, one dime, one quarter, one nickel, and a penny. The number of different sums of money that can be formed using three coins is... Answered by Penny Nom. |
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6-49 |
2000-09-14 |
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From Steve: In our state lottery you must choose 6 numbers (1-49). How many different combinations are there? They can be in any order. Answered by Harley Weston. |
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Binomial coefficients |
2000-03-21 |
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From Howard Lutz: How do you find each successive numerical term in this equation y+dy=(x+dx)5 =x5+5*x4dx+10*x3(dx)2+10*x^2(dx)3+5*x(dx)4+(dx)5 I would appreciate an explanation of the method to find the numeric coefficient in a binomial expansion Answered by Penny Nom. |
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Multinomial coefficients |
1999-12-03 |
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From Suraj Das: Is there a formula for the expansion of (a+b+c) to the nth power? Does it have to do with Pascal's triangle? Answered by Penny Nom. |
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Cannonballs |
1999-01-27 |
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From Roger King: How many cannonballs can be stacked in a triangular pyramid? Answered by Penny Nom. |
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