Mathematics - Online Test

Q1.  is equal to
Answer : Option D
Explaination / Solution:

  
Q2. If P ( n ) = 2+4+6+………………..+2n , n  N , then P ( k ) = k ( k + 1 ) + 2  P ( k + 1 ) = ( k + 1 ) ( k +2 ) + 2 for all k  N . So we can conclude that P ( n ) = n ( n + 1 ) +2 for
Answer : Option B
Explaination / Solution:

Because the statement is incomplete without the conclusion/ RHS

Q3.

The equation  represents


Answer : Option C
Explaination / Solution:

The above circle can be written as   Here the center is (0,0) and radius is also 0 units.

So it is a degenerate circle as  degenerate circle is a circle( a point) where radius is zero units.


Q4. Number of ways in which 10 different things can be divided into two groups containing 6 and 4 things respectively is
Answer : Option A
Explaination / Solution:

If there are 10 things and we have  to make them in to two groups containing 6 things and 4 things respectively , you have to select 6 to form first group , then automatically another group would have formed of 4 remaining things.

Now 6 things can be selected from 10 things in  different ways

Also we have   


Q5. The order of the equation  is
Answer : Option B
Explaination / Solution:

Since the equation has 2nd derivative as the highest derivative term.hence the order 2

Q6. If l, m and n are the direction cosines of a line, Direction ratios of the line are the numbers which are
Answer : Option C
Explaination / Solution:

If l, m and n are the direction cosines of a line, Direction ratios of the line are the numbers which are Proportional to the direction cosines of the line.

Q7. There exists a triangle ABC satisfying the conditions
Answer : Option D
Explaination / Solution:


when k=1 we have 


But we have  in a triangle the sum of the  three angles is 180 degrees ,so if B=90 degrees then A<π2 


Q8. Area of the region bounded by the curves y = , x = a , x = b and the x- axis is given by
Answer : Option A
Explaination / Solution:

Required area
abexdx=[ex]ba=ebea

Q9. The direction cosines of any normal to the XY plane are
Answer : Option D
Explaination / Solution:

Concept used - Parellel lines have same direction cosines

Explanation We know Z axis is perpendicular to XY plane and direction cosines of Z axis are <0,0,1>

and as  any normal to XY plane will be parallel to Z axis and parellel lines have same direction cosines so answer is <0,0,1>


Q10. If P is of order 2 × 3 and Q is of order 3 × 2, then PQ is of order
Answer : Option B
Explaination / Solution:

Here, matrix P is of order  and matrix Q is of order  , then , the product PQ is defined only when : no. of columns in P = no. of rows in Q. And the order of resulting matrix is given by : rows in P x columns in Q.