NCERT Solutions for Class 12 Maths Chapter 4 Determinants Exercise 4.2

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CBSE CLASS XII Related Questions

  • 1.
    If \[ P = \begin{bmatrix} 1 & -1 & 0 \\ 2 & 3 & 4 \\ 0 & 1 & 2 \end{bmatrix} \quad \text{and} \quad Q = \begin{bmatrix} 2 & 2 & -4 \\ -4 & 2 & -4 \\ 1 & -1 & 5 \end{bmatrix} \] find \( QP \) and hence solve the following system of equations using matrix method:
    \[ x - y = 3,\quad 2x + 3y + 4z = 13,\quad y + 2z = 7 \]


      • 2.
        Find the sub–interval of \((0,\pi)\) in which the function \[ f(x)=\tan^{-1}(\sin x-\cos x) \] is increasing and decreasing.


          • 3.

            Smoking increases the risk of lung problems. A study revealed that 170 in 1000 males who smoke develop lung complications, while 120 out of 1000 females who smoke develop lung related problems. In a colony, 50 people were found to be smokers of which 30 are males. A person is selected at random from these 50 people and tested for lung related problems. Based on the given information answer the following questions: 

            (i) What is the probability that selected person is a female? 
            (ii) If a male person is selected, what is the probability that he will not be suffering from lung problems? 
            (iii)(a) A person selected at random is detected with lung complications. Find the probability that selected person is a female. 
            OR 
            (iii)(b) A person selected at random is not having lung problems. Find the probability that the person is a male. 
             


              • 4.

                A rectangle of perimeter \(24\) cm is revolved along one of its sides to sweep out a cylinder of maximum volume. Find the dimensions of the rectangle. 


                  • 5.
                    Obtain the value of \[ \Delta = \begin{vmatrix} 1 + x & 1 & 1 \\ 1 & 1 + y & 1 \\ 1 & 1 & 1 + z \end{vmatrix} \] in terms of \(x, y, z\). Further, if \(\Delta = 0\) and \(x, y, z\) are non–zero real numbers, prove that \[ x^{-1} + y^{-1} + z^{-1} = -1 \]


                      • 6.

                        The probability of hitting the target by a trained sniper is three times the probability of not hitting the target on a stormy day due to high wind speed. The sniper fired two shots on the target on a stormy day when wind speed was very high. Find the probability that 
                        (i) target is hit. 
                        (ii) at least one shot misses the target. 

                          CBSE CLASS XII Previous Year Papers

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