CBSE 12TH MATHEMATICS - Online Test

Q1. Differential equation of the family of ellipses having foci on y-axis and centre at origin is
Answer : Option A
Explaination / Solution:



Q2.

A dietician wishes to mix together two kinds of food X and Y in such a way that the mixture contains at least 10 units of vitamin A, 12 units of vitamin B and 8 units of vitamin C. The vitamin contents of one kg food is given below:

Food

Vitamin A

Vitamin B

Vitamin C

X

1

2

3

Y

2

2

1

One kg of food X costs Rs 16 and one kg of food Y costs Rs 20. Find the least cost of the mixture which will produce the required diet?

Answer : Option A
Explaination / Solution:

Let number of kgs of food of brand X = x
And number of kgs. of food of brand Y = y
Therefore , the above L.P.P. is given as :
Minimise , Z = 16x +20y , subject to the constraints : x + 2y ≥ 10,2x + 2y ≥12,3x + y ≥8,x,y ≥ 0.,

 

Corner points

Z =16x +20 y

C(10 , 0 )

160

 

B (0,8)

160

D(1,5 )      

116

A(2,4)

112……………..(Min.)


Here Z = 112 is minimum.
i.e. Least cost of the mixture is Rs 112 (2 kg of Food X and 4 kg of food Y).


Q3. The maximum value of  is
Answer : Option A
Explaination / Solution:



Q4. The range of the function f(x) =|x−1| is
Answer : Option C
Explaination / Solution:

We have , f(x) =|x−1|, which always gives non-negative values of f(x) for all x∈R.Therefore range of the given function is all non-negative real numbers i.e. [0,∞] .

Q5. The inverse of the matrix A = 
Answer : Option C
Explaination / Solution:



Q6.

The area bounded by the curves and  is equal to


Answer : Option D
Explaination / Solution:

Eliminating y, we get:

Required area:



Q7. If a is a non zero vector of magnitude ‘a’ and  a non zero scalar, then    is a unit vector if
Answer : Option B
Explaination / Solution:

   is a unit vector if and only if a is equal to .

Q8.  dx is equal to
Answer : Option B
Explaination / Solution:



Q9.

Domain of f(x) = 


Answer : Option A
Explaination / Solution:

(1,1)
Q10.

If A and B are square matrices of the same order, then implies


Answer : Option C
Explaination / Solution:

If A and B are square matrices of same order , then , product of the matrices is not commutative.Therefore , the given result is true only when AB = BA.