Maths-

General

Easy

Question

# If n and are integers such that then n c (n‐l, r‐l)=

- C(n,r)
- n C(n,r)
- rC(n,r)
- (n‐ 1) C(n,r)

## The correct answer is: rC(n,r)

### Related Questions to study

maths-

maths-General

maths-

### The least value of the natural number n satisfying

### The least value of the natural number n satisfying

maths-General

maths-

### then (n, r)=

### then (n, r)=

maths-General

maths-

### then ‘n’ is

### then ‘n’ is

maths-General

Maths-

### If = mC_{2}, then C_{2} is equal to -

Students must know how to open expressions like nCr.

Also, the value of n! is n.(n−1).(n−2).....3.2.1.

Combination is used to select r objects from n objects when the arrangement of the objects does not matter.

### If = mC_{2}, then C_{2} is equal to -

Maths-General

Students must know how to open expressions like nCr.

Also, the value of n! is n.(n−1).(n−2).....3.2.1.

Combination is used to select r objects from n objects when the arrangement of the objects does not matter.

Maths-

### Twelve students compete for a race. The number of ways in which first three places can be taken, is-

### Twelve students compete for a race. The number of ways in which first three places can be taken, is-

Maths-General

Maths-

### Given the circuit :

Which of the following is equivalent to the above circuit ?

I)

II)

The true statement in the above is / are

### Given the circuit :

Which of the following is equivalent to the above circuit ?

I)

II)

The true statement in the above is / are

Maths-General

Maths-

### The symbolic form of logic of the circuit given below is

### The symbolic form of logic of the circuit given below is

Maths-General

Maths-

### The following circuit when expressed in the symbolic form of logic is

### The following circuit when expressed in the symbolic form of logic is

Maths-General

chemistry-

### For conversion C(graphite)→C(Diamond),the DS is-

### For conversion C(graphite)→C(Diamond),the DS is-

chemistry-General

chemistry-

### Consider the following processes: DH(kJ/mol) ½A→B +150 3B→2C+D–125 E+A→2D+350 ForB+D→E+2C,DHillbe-

### Consider the following processes: DH(kJ/mol) ½A→B +150 3B→2C+D–125 E+A→2D+350 ForB+D→E+2C,DHillbe-

chemistry-General

chemistry-

### Enthalpy change for the reaction, 4H_{(g)} →2H_{2(g)} is–869.6kJ The dissociation energy of H–H bond is

### Enthalpy change for the reaction, 4H_{(g)} →2H_{2(g)} is–869.6kJ The dissociation energy of H–H bond is

chemistry-General

chemistry-

### ThevaluesofDHandDSforthereaction,C(graphite)+CO(g)→2CO(g)are170kJand170 JK–1respectively.Thisreactionwillbespontaneousat

### ThevaluesofDHandDSforthereaction,C(graphite)+CO(g)→2CO(g)are170kJand170 JK–1respectively.Thisreactionwillbespontaneousat

chemistry-General

maths-

### Assertion: The sum of all4 digited numbers that can be formed using the digits 1,2,4,5,6 without repetition is 479952

Reason: Sum of all ‐digit numbers formed by taking the given n digits (without zero) is (sum of all the n digits) ( times).

### Assertion: The sum of all4 digited numbers that can be formed using the digits 1,2,4,5,6 without repetition is 479952

Reason: Sum of all ‐digit numbers formed by taking the given n digits (without zero) is (sum of all the n digits) ( times).

maths-General

maths-

### Assertion: There are three doors to a room The number of ways in which a student can enter the room and leave it by a different door is 6.

Reason: If an operation can be performed in ways and another operation can be perfO rmed in ways thenthe two operations in succession can be performed in mn ways.

### Assertion: There are three doors to a room The number of ways in which a student can enter the room and leave it by a different door is 6.

Reason: If an operation can be performed in ways and another operation can be perfO rmed in ways thenthe two operations in succession can be performed in mn ways.

maths-General