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Recent questions tagged binomial-theorem
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TIFR CSE 2022 | Part B | Question: 9
Let $n \geq 2$ be any integer. Which of the following statements is $\text{FALSE}?$ $n!$ divides the product of any $n$ consecutive integers $\displaystyle{}\sum_{i=0}^n\left(\begin{array}{c}n \\ i\end{array}\right)=2^n$ ... an odd prime, then $n$ divides $2^{n-1}-1$ $n$ divides $\left(\begin{array}{c}2 n \\ n\end{array}\right)$
Let $n \geq 2$ be any integer. Which of the following statements is $\text{FALSE}?$$n!$ divides the product of any $n$ consecutive integers$\displaystyle{}\sum_{i=0}^n\le...
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Sep 1, 2022
Combinatory
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TIFR CSE 2021 | Part A | Question: 10
Lavanya and Ketak each flip a fair coin (i.e., both heads and tails have equal probability of appearing) $n$ times. What is the probability that Lavanya sees more heads than ketak? In the following, the binomial coefficient $\binom{n}{k}$ counts the number of $k$-element subsets of ... $\sum_{i=0}^{n}\frac{\binom{n}{i}}{2^{n}}$
Lavanya and Ketak each flip a fair coin (i.e., both heads and tails have equal probability of appearing) $n$ times. What is the probability that Lavanya sees more heads t...
soujanyareddy13
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soujanyareddy13
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Mar 25, 2021
Probability
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TIFR CSE 2021 | Part A | Question: 12
How many numbers in the range ${0, 1, \dots , 1365}$ have exactly four $1$'s in their binary representation? (Hint: $1365_{10}$ is $10101010101_{2}$, that is, $1365=2^{10} + 2^{8}+2^{6}+2^{4}+2^{2}+2^{0}.)$ ... $\binom{11}{4}+\binom{9}{3}+\binom{7}{2}+\binom{5}{1}$ $1024$
How many numbers in the range ${0, 1, \dots , 1365}$ have exactly four $1$’s in their binary representation? (Hint: $1365_{10}$ is $10101010101_{2}$, that is, $$1365=2^...
soujanyareddy13
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Mar 25, 2021
Digital Logic
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Kenneth Rosen Edition 7 Exercise 6.4 Question 39 (Page No. 422 - 423)
Determine a formula involving binomial coefficients for the nth term of a sequence if its initial terms are those listed. [Hint: Looking at Pascal's triangle will be helpful. Although infinitely many sequences start with a specified set of terms, ... $1, 3, 15, 84, 495, 3003, 18564, 116280, 735471, 4686825,\dots$
Determine a formula involving binomial coefficients for the nth term of a sequence if its initial terms are those listed. [Hint: Looking at Pascal’s triangle will be he...
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497
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Apr 30, 2020
Combinatory
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discrete-mathematics
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Kenneth Rosen Edition 7 Exercise 6.4 Question 38 (Page No. 422)
Give a combinatorial proof that if n is a positive integer then $\displaystyle\sum_{k = 0}^{n} k^{2} \binom{n} {k} = n(n + 1)2^{n−2}.$ [Hint: Show that both sides count the ways to select a subset of a set of ... necessarily distinct elements from this subset. Furthermore, express the right-hand side as $n(n − 1)2^{n−2} + n2^{n−1}.]$
Give a combinatorial proof that if n is a positive integer then $\displaystyle\sum_{k = 0}^{n} k^{2} \binom{n} {k} = n(n + 1)2^{n−2}.$ [Hint: Show that both sides count...
admin
366
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Apr 30, 2020
Combinatory
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discrete-mathematics
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Kenneth Rosen Edition 7 Exercise 6.4 Question 37 (Page No. 422)
Use question $33$ to prove the hockeystick identity from question $27.$ [Hint: First, note that the number of paths from $(0, 0)\: \text{to}\: (n + 1,r)$ equals $\binom{n + 1 + r}{r}.$ Second, count the number of paths by summing the number of these paths that start by going $k$ units upward for $k = 0, 1, 2,\dots,r.]$
Use question $33$ to prove the hockeystick identity from question $27.$ [Hint: First, note that the number of paths from $(0, 0)\: \text{to}\: (n + 1,r)$ equals $\binom{n...
admin
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Apr 30, 2020
Combinatory
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Kenneth Rosen Edition 7 Exercise 6.4 Question 36 (Page No. 422)
Use question $33$ to prove Pascal’s identity. [Hint: Show that a path of the type described in question $33$ from $(0, 0)\: \text{to}\: (n + 1 − k, k)$ passes through either $(n + 1 − k, k − 1)\: \text{or} \:(n − k, k),$ but not through both.]
Use question $33$ to prove Pascal’s identity. [Hint: Show that a path of the type described in question $33$ from $(0, 0)\: \text{to}\: (n + 1 − k, k)$ passes through...
admin
237
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admin
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Apr 30, 2020
Combinatory
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Kenneth Rosen Edition 7 Exercise 6.4 Question 35 (Page No. 422)
Use question $33$ to prove Theorem $4.$ [Hint: Count the number of paths with n steps of the type described in question $33.$ Every such path must end at one of the points $(n − k, k)\:\text{for}\: k = 0, 1, 2,\dots,n.]$
Use question $33$ to prove Theorem $4.$ [Hint: Count the number of paths with n steps of the type described in question $33.$ Every such path must end at one of the point...
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admin
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Apr 30, 2020
Combinatory
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Kenneth Rosen Edition 7 Exercise 6.4 Question 34 (Page No. 422)
Use question $33$ to give an alternative proof of Corollary $2$ in Section $6.3,$ which states that $\binom{n}{k} = \binom{n}{n−k} $ whenever $k$ is an integer with $0 \leq k \leq n.[$Hint: Consider the number of paths of the type described in question $33$ ... $(0, 0)\: \text{to}\:(k, n − k).]$
Use question $33$ to give an alternative proof of Corollary $2$ in Section $6.3,$ which states that $\binom{n}{k} = \binom{n}{n−k} $ whenever $k$ is an integer with $0 ...
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Apr 30, 2020
Combinatory
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Kenneth Rosen Edition 7 Exercise 6.4 Question 33 (Page No. 422)
In this exercise we will count the number of paths in the $xy$ plane between the origin $(0, 0)$ and point $(m, n),$ where $m$ and $n$ are nonnegative integers, such that each path is made up of a series of steps, where each ... move one unit upward. Conclude from part $(A)$ that there are $\binom{m + n}{n}$ paths of the desired type.
In this exercise we will count the number of paths in the $xy$ plane between the origin $(0, 0)$ and point $(m, n),$ where $m$ and $n$ are nonnegative integers, such that...
admin
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admin
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Apr 30, 2020
Combinatory
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discrete-mathematics
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Kenneth Rosen Edition 7 Exercise 6.4 Question 32 (Page No. 422)
Prove the binomial theorem using mathematical induction.
Prove the binomial theorem using mathematical induction.
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172
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admin
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Apr 30, 2020
Combinatory
kenneth-rosen
discrete-mathematics
counting
binomial-theorem
proof
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Kenneth Rosen Edition 7 Exercise 6.4 Question 31 (Page No. 422)
Show that a nonempty set has the same number of subsets with an odd number of elements as it does subsets with an even number of elements.
Show that a nonempty set has the same number of subsets with an odd number of elements as it does subsets with an even number of elements.
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214
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Apr 30, 2020
Combinatory
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discrete-mathematics
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Kenneth Rosen Edition 7 Exercise 6.4 Question 30 (Page No. 422)
Give a combinatorial proof that $\displaystyle{}\sum_{k = 1}^{n} k \binom{n}{k}^{2} = n \binom{2n−1}{n−1}.$ [Hint: Count in two ways the number of ways to select a committee, with $n$ members ... of $n$ mathematics professors and $n$ computer science professors, such that the chairperson of the committee is a mathematics professor.]
Give a combinatorial proof that $\displaystyle{}\sum_{k = 1}^{n} k \binom{n}{k}^{2} = n \binom{2n−1}{n−1}.$ [Hint: Count in two ways the number of ways to select a co...
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admin
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Apr 30, 2020
Combinatory
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discrete-mathematics
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Kenneth Rosen Edition 7 Exercise 6.4 Question 29 (Page No. 422)
Give a combinatorial proof that $\displaystyle{}\sum_{k = 1}^{n} k \binom{n}{k} = n2^{n−1}.$ [Hint: Count in two ways the number of ways to select a committee and to then select a leader of the committee.]
Give a combinatorial proof that $\displaystyle{}\sum_{k = 1}^{n} k \binom{n}{k} = n2^{n−1}.$ [Hint: Count in two ways the number of ways to select a committee and to th...
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admin
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Apr 30, 2020
Combinatory
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discrete-mathematics
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Kenneth Rosen Edition 7 Exercise 6.4 Question 28 (Page No. 422)
Show that if $n$ is a positive integer, then $\binom{2n}{2} = 2\binom{n}{2} + n^{2} $ using a combinatorial argument. by algebraic manipulation.
Show that if $n$ is a positive integer, then $\binom{2n}{2} = 2\binom{n}{2} + n^{2} $ using a combinatorial argument. by algebraic manipulation.
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Apr 30, 2020
Combinatory
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discrete-mathematics
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Kenneth Rosen Edition 7 Exercise 6.4 Question 27 (Page No. 422)
Prove the hockeystick identity $\displaystyle{}\sum_{k=0}^{r} \binom{n + k}{k} = \binom{n + r + 1}{r}$ whenever $n$ and $r$ are positive integers, using a combinatorial argument. using Pascal’s identity.
Prove the hockeystick identity $\displaystyle{}\sum_{k=0}^{r} \binom{n + k}{k} = \binom{n + r + 1}{r}$ whenever $n$ and $r$ are positive integers, using a combinatorial a...
admin
254
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admin
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Apr 30, 2020
Combinatory
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discrete-mathematics
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Kenneth Rosen Edition 7 Exercise 6.4 Question 26 (Page No. 422)
Let $n$ and $k$ be integers with $1 \leq k \leq n.$ Show that $\displaystyle{}\sum_{k=1}^{n} \binom{n}{k}\binom{n}{k − 1} = \dfrac{\binom{2n + 2}{n + 1}}{2} − \binom{2n}{n}.$
Let $n$ and $k$ be integers with $1 \leq k \leq n.$ Show that $\displaystyle{}\sum_{k=1}^{n} \binom{n}{k}\binom{n}{k − 1} = \dfrac{\binom{2n + 2}{n + 1}}{2} − \binom{...
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admin
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Apr 30, 2020
Combinatory
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discrete-mathematics
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Kenneth Rosen Edition 7 Exercise 6.4 Question 25 (Page No. 422)
Let n be a positive integer. Show that $\binom{2n}{n + 1} + \binom{2n}{n} = \dfrac{\binom{2n + 2}{n + 1}}{2}.$
Let n be a positive integer. Show that $\binom{2n}{n + 1} + \binom{2n}{n} = \dfrac{\binom{2n + 2}{n + 1}}{2}.$
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Apr 30, 2020
Combinatory
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discrete-mathematics
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Kenneth Rosen Edition 7 Exercise 6.4 Question 24 (Page No. 422)
Show that if $p$ is a prime and $k$ is an integer such that $1 \leq k \leq p − 1,$ then $p$ divides $\binom{p}{k} .$
Show that if $p$ is a prime and $k$ is an integer such that $1 \leq k \leq p − 1,$ then $p$ divides $\binom{p}{k} .$
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206
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Apr 30, 2020
Combinatory
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discrete-mathematics
counting
binomial-theorem
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Kenneth Rosen Edition 7 Exercise 6.4 Question 23 (Page No. 422)
Show that if $n$ and $k$ are positive integers, then $\binom{n + 1}{k} = \dfrac{(n + 1)\binom {n}{k – 1}}{k}.$ Use this identity to construct an inductive definition of the binomial coefficients.
Show that if $n$ and $k$ are positive integers, then $\binom{n + 1}{k} = \dfrac{(n + 1)\binom {n}{k – 1}}{k}.$ Use this identity to construct an inductive definition of...
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Apr 30, 2020
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discrete-mathematics
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Kenneth Rosen Edition 7 Exercise 6.4 Question 22 (Page No. 422)
Prove the identity $\binom{n}{r}\binom{r}{k} = \binom{n}{k}\binom{n−k}{r−k} ,$ whenever $n, r,$ and $k$ are nonnegative integers with $r \leq n$ and $k \leq r,$ using a combinatorial argument. using an argument based on the formula for the number of $r$-combinations of a set with $n$ elements.
Prove the identity $\binom{n}{r}\binom{r}{k} = \binom{n}{k}\binom{n−k}{r−k} ,$ whenever $n, r,$ and $k$ are nonnegative integers with $r \leq n$ and $k \leq r,$using ...
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Apr 30, 2020
Combinatory
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Kenneth Rosen Edition 7 Exercise 6.4 Question 21 (Page No. 422)
Prove that if $n$ and $k$ are integers with $1 \leq k \leq n,$ then $k \binom{n}{k} = n \binom{n−1}{k−1},$ using a combinatorial proof. [Hint: Show that the two sides of the identity count the number of ways to select ... subset.] using an algebraic proof based on the formula for $\binom{n}{r}$ given in Theorem $2$ in Section $6.3.$
Prove that if $n$ and $k$ are integers with $1 \leq k \leq n,$ then $k \binom{n}{k} = n \binom{n−1}{k−1},$using a combinatorial proof. [Hint: Show that the two sides ...
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Apr 30, 2020
Combinatory
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Kenneth Rosen Edition 7 Exercise 6.4 Question 20 (Page No. 421)
Suppose that $k$ and $n$ are integers with $1 \leq k<n.$ Prove the hexagon identity $\binom{n-1}{k-1}\binom{n}{k+1}\binom{n+1}{k} = \binom{n-1}{k}\binom{n}{k-1}\binom{n+1}{k+1},$ which relates terms in Pascal’s triangle that form a hexagon.
Suppose that $k$ and $n$ are integers with $1 \leq k<n.$ Prove the hexagon identity $\binom{n-1}{k-1}\binom{n}{k+1}\binom{n+1}{k} = \binom{n-1}{k}\binom{n}{k-1}\binom{n+1...
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admin
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Apr 30, 2020
Combinatory
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Kenneth Rosen Edition 7 Exercise 6.4 Question 19 (Page No. 421)
Prove Pascal’s identity, using the formula for $\binom{n}{r}.$
Prove Pascal’s identity, using the formula for $\binom{n}{r}.$
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Apr 30, 2020
Combinatory
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Kenneth Rosen Edition 7 Exercise 6.4 Question 18 (Page No. 421)
Suppose that $b$ is an integer with $b \geq 7.$ Use the binomial theorem and the appropriate row of Pascal’s triangle to find the base-$b$ expansion of $(11)^{4}_{b}$ [that is, the fourth power of the number $(11)_{b}$ in base-$b$ notation].
Suppose that $b$ is an integer with $b \geq 7.$ Use the binomial theorem and the appropriate row of Pascal’s triangle to find the base-$b$ expansion of $(11)^{4}_{b}$ [...
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Apr 30, 2020
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Kenneth Rosen Edition 7 Exercise 6.4 Question 17 (Page No. 421)
Show that if $n$ and $k$ are integers with $1 \leq k \leq n,$ then $\binom{n}{k} \leq \frac{n^{k}}{2^{k−1}}.$
Show that if $n$ and $k$ are integers with $1 \leq k \leq n,$ then $\binom{n}{k} \leq \frac{n^{k}}{2^{k−1}}.$
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Apr 30, 2020
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