Business Mathematics
181. If probability P( n, r) =720 and combination C(n, r) =120 then r is
- 9
- 8
- 5
- 3
Correct answer: (D)
3
182. For 1) 2a +c -2d = 5
2) –a +2b +c = 4
3) +b -c +3d = 1
4) 2a -b +2c -5d = 4
- Equation 1 is dependent on 3 and 4
- Equation 2 is dependent on 3 and 4
- Equation 1 is dependent on 2 and 3
- None
Correct answer: (A)
Equation 1 is dependent on 3 and 4
183. Is xyz
- Non linear
- Linear
- Binomial
- None
Correct answer: (A)
Non linear
184. Inverse of a square matrix A, denoted by A-1 is also a square matrix of the same order such that A A-1 is
- A-1
- A
- I
- AI
Correct answer: (C)
I
185. A diagonal matrix in which all diagonal elements are equal is called
- Unit matrix
- Null matrix
- Scalar matrix
- Triangular matrix
Correct answer: (C)
Scalar matrix
186. If A, B are symmetric matrices of the same order, then AB – BA is a
- Skew symmetric matrix
- Symmetric matrix
- Zero matrix
- Identity matrix
Correct answer: (A)
Skew symmetric matrix
187. If A = a b is such that A2 = I, then c - a
- 1+ a2 + bc =0
- 1 –a2 + bc =0
- 1 –a2 -bc = 0
- 1 +a2 -bc=0
Correct answer: (B)
1 –a2 -bc = 0
188. Let A be a square matrix of order 3 x 3, then | kA | is equal to
- k | A |
- k2 | A |
- k3 | A |
- 3k | A |
Correct answer: (C)
k3 | A |
189. Equation of line joining (1,2) and (3,6) using determinants is
- y = 3x
- y =2x
- x = 2y
- x =3x
Correct answer: (B)
y =2x
190. If A is an invertible matrix of order 2, then det( A-1) is equal to
- det( A)
- 1/det( A)
- 1
- 0
Correct answer: (B)
1/det( A)