Maths-
General
Easy
Question
If n objects are arranged in a row, then the number of ways of selecting three of these objects so that no two of them are next to each other is -
- n – 2C3
- n – 3C2
- n – 3C3
- None of these
The correct answer is: n – 2C3
Related Questions to study
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The number of numbers between 1 and 1010 which contain the digit 1 is -
The number of numbers between 1 and 1010 which contain the digit 1 is -
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The number of rectangles in the adjoining figure is –

The number of rectangles in the adjoining figure is –

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chemistry-
Assertion :this equilibrium favours backward direction.
Reason :
is stronger base than 
Assertion :this equilibrium favours backward direction.
Reason :
is stronger base than 
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A 0.098 kg block slides down a frictionless track as shown. The vertical component of the velocity of block at
is

Vertical component at
A 0.098 kg block slides down a frictionless track as shown. The vertical component of the velocity of block at
is

Physics-General
Vertical component at
physics-
Two small particles of equal masses start moving in opposite directions from a point A in a horizontal circular orbit. Their tangential velocities are
respectively, as shown in the figure. Between collisions, the particles move with constant speeds. After making how many elastic collisions, other than that at
,these two particles will again reach The point 

A s first collision one particle having speed 2v will rotate
while other particle having speed
will rotate
At first collision they will exchange their velocities. Now as shown in figure, after two collisions they will again reach at point A.


Two small particles of equal masses start moving in opposite directions from a point A in a horizontal circular orbit. Their tangential velocities are
respectively, as shown in the figure. Between collisions, the particles move with constant speeds. After making how many elastic collisions, other than that at
,these two particles will again reach The point 

physics-General
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while other particle having speed
will rotate
At first collision they will exchange their velocities. Now as shown in figure, after two collisions they will again reach at point A.


physics-
The trajectory of a particle moving in vast maidan is as shown in the figure. The coordinates of a position
are
The coordinates of another point at which the instantaneous velocity is same as the average velocity between the points are

The trajectory of a particle moving in vast maidan is as shown in the figure. The coordinates of a position
are
The coordinates of another point at which the instantaneous velocity is same as the average velocity between the points are

physics-General
physics-
The potential energy of a particle varies with distance
as shown in the graph.
The force acting on the particle is zero at

The potential energy of a particle varies with distance
as shown in the graph.
The force acting on the particle is zero at

physics-General
physics-
A
mass moves along
-axis. Its acceleration as a function of its position is shown in the figure. What is the total work done on the mass by the force as the mass moves from
to 

Work done = Area covered in between force displacement curve and displacement axis
= Mass
Area covered in between acceleration-displacement curve and displacement axis

= Mass
A
mass moves along
-axis. Its acceleration as a function of its position is shown in the figure. What is the total work done on the mass by the force as the mass moves from
to 

physics-General
Work done = Area covered in between force displacement curve and displacement axis
= Mass
Area covered in between acceleration-displacement curve and displacement axis

= Mass
physics-
A mass
slips along the wall of a semispherical surface of radius
. The velocity at the bottom of the surface is

By applying law of conservation of energy

A mass
slips along the wall of a semispherical surface of radius
. The velocity at the bottom of the surface is

physics-General
By applying law of conservation of energy

physics-
Three forces of magnitudes 6N, 6N and
N at a corner of a cube along three sides as shown in figure. Resultant of these forces is

The resultant of 5 N along
and 5 N along
is

N along 
The resultant of
N along
and
N along
is
N along
.
The resultant of
Three forces of magnitudes 6N, 6N and
N at a corner of a cube along three sides as shown in figure. Resultant of these forces is

physics-General
The resultant of 5 N along
and 5 N along
is

N along 
The resultant of
N along
and
N along
is
N along
.
The resultant of
physics-
A man standing on a hill top projects a stone horizontally with speed
as shown in figure. Taking the coordinate system as given in the figure. The coordinates of the point where the stone will hit the hill surface
Range of the projectile on an inclined plane (down the plane) is,

Here,
and 


Now
and
Here,

Now
and
A man standing on a hill top projects a stone horizontally with speed
as shown in figure. Taking the coordinate system as given in the figure. The coordinates of the point where the stone will hit the hill surface
physics-General
Range of the projectile on an inclined plane (down the plane) is,

Here,
and 


Now
and
Here,

Now
and
physics-
A particle is acted upon by a force
which varies with position
as shown in the figure. If the particle at
has kinetic energy of 25 J, then the kinetic energy of the particle at
is

Work done
Area under
-
graph with proper sign
Area of triangle
+ Area of rectangle
+ Area of rectangle
+ Area of 


….(i)
According to work energy theorem


[Using (i)]

According to work energy theorem
A particle is acted upon by a force
which varies with position
as shown in the figure. If the particle at
has kinetic energy of 25 J, then the kinetic energy of the particle at
is

physics-General
Work done
Area under
-
graph with proper sign
Area of triangle
+ Area of rectangle
+ Area of rectangle
+ Area of 


….(i)
According to work energy theorem


[Using (i)]

According to work energy theorem
physics-
A bob of mass
accelerates uniformly from rest to
in time
. As a function of
, the instantaneous power delivered to the body is

From 

Velocity acquired in
sec 
Power
Velocity acquired in
Power
A bob of mass
accelerates uniformly from rest to
in time
. As a function of
, the instantaneous power delivered to the body is

physics-General
From 

Velocity acquired in
sec 
Power
Velocity acquired in
Power
physics-
An aeroplane is flying in a horizontal direction with a velocity
at a height of 1960 m. when it is vertically above the point
on the ground, a body is dropped from it. The body strikes the ground at point
. Calculate the distance 

From 
We have

Horizontal distance


We have
Horizontal distance
An aeroplane is flying in a horizontal direction with a velocity
at a height of 1960 m. when it is vertically above the point
on the ground, a body is dropped from it. The body strikes the ground at point
. Calculate the distance 

physics-General
From 
We have

Horizontal distance


We have
Horizontal distance
Maths-
If the equation
represents an ellipse then
If the equation
represents an ellipse then
Maths-General