Aspire Faculty ID #15281 · Topic: JAMIA MCA 2016 · Just now
JAMIA MCA 2016

If ${}^8C_r - {}^7C_3 = {}^7C_2$, then $r$ is equal to …

Solution

We know ${}^8C_r = {}^7C_{r} + {}^7C_{r-1}$. So, ${}^8C_r - {}^7C_3 = {}^7C_{r} + {}^7C_{r-1} - {}^7C_3 = {}^7C_2$. Comparing, ${}^7C_{r-1} = {}^7C_3 \Rightarrow r - 1 = 3 \Rightarrow r = 4$.
← Previous Next →

Previous 10 Questions — JAMIA MCA 2016

Nearest first
1
If sum of $n$ terms of a series is $3n^2 + 4n$, then the series is …
Topic: JAMIA MCA 2016
 2
If $\log_{2}(5\cdot2^{x}+1),\ \log_{4}(2^{\,1-x}+1)$ and $1$ are in A.P., then $x$ equals …
Topic: JAMIA MCA 2016
 3
If the roots of $x^3-9x^2+23x-15=0$ are in A.P., then their common difference is …
Topic: JAMIA MCA 2016
 4
Let sum of $n$ terms of an A.P. be $S_n=3n^2+5$. If $T_n$ (the $n$th term) of this series is $159$, then $n$ is …
Topic: JAMIA MCA 2016
 5
If $m^{\text{th}}$ term of an A.P. is $n$ and $n^{\text{th}}$ term is $m$, then its $10^{\text{th}}$ term is …
Topic: JAMIA MCA 2016
 6
Let cube roots of unity be $1, \omega, \omega^{2}$. Which of the following is a cube root of the equation $(x - 1)^{3} …
Topic: JAMIA MCA 2016
 7
If $\omega$ is a cube root of unity, then the value of $(1 + \omega - \omega^{2})(1 - \omega + \omega^{2})$ is …
Topic: JAMIA MCA 2016
 8
If $z$ be a complex number, then one of the solutions of the equation $z^{2} + |z|^{2} = 0$ is …
Topic: JAMIA MCA 2016
 9
If $z$ be a complex number and $\bar{z}$ be its conjugate, then the number of solutions of $z^{2} + 2\bar{z} = 0$ is …
Topic: JAMIA MCA 2016
 10
The amplitude of $\dfrac{1+i\sqrt{3}}{\sqrt{3}+i}$ is equal to …
Topic: JAMIA MCA 2016

Next 10 Questions — JAMIA MCA 2016

Ascending by ID
1
The number of arrangements of the letters of the word BANANA in which two N’s do not appear adjacently is …
Topic: JAMIA MCA 2016
 2
The number of numbers greater than 23000 that can be formed from the digits 1, 2, 3, 4, 5 is …
Topic: JAMIA MCA 2016
 3
The coefficient of $x^8 y^{10}$ in $(x + y)^{18}$ is …
Topic: JAMIA MCA 2016
 4
The coefficient of $x^4$ in expansion of $(1 + x + x^2 + x^3)^{11}$ is …
Topic: JAMIA MCA 2016
 5
If $A$ be a set of cardinality $n$, then number of one-to-one onto functions from set $A$ to $A$ is …
Topic: JAMIA MCA 2016
 6
If $f$ is a function from a finite set $A$ having $10$ elements to a finite set $B$ having $5$ elements, then number of…
Topic: JAMIA MCA 2016
 7
If $A$ and $B$ are two sets, then $(A \cup B)' \cap B$ is equal to …
Topic: JAMIA MCA 2016
 8
If $A = \{a, b, c\}$ and $B = \{a, b, d, e, f\}$ are two sets, then number of elements in $(A - B) \times (A \cap B)$ i…
Topic: JAMIA MCA 2016
 9
If $A$ and $B$ are two disjoint sets having $3$ and $5$ elements respectively, then power-set of $A \times (B - A)$ con…
Topic: JAMIA MCA 2016
 10
If $y = \tan^{-1}\!\left(\dfrac{1 + \tan x}{1 - \tan x}\right)$, then $\dfrac{dy}{dx}$ is equal to …
Topic: JAMIA MCA 2016
Ask Your Question or Put Your Review.

loading...