12th Class Mathematics Applications of Derivatives Question Bank Assertion And Reason (MCQs) - Applications of Derivatives

  • question_answer
    Assertion [A]: The tangent to the curve \[y={{x}^{3}}-{{x}^{2}}-x+2\] at (1, 1) is parallel to the X-axis.
    Reason [R]: The slope of the tangent to the above curve at (1, 1) is zero.
     

    A) Both A and R are individually true and R is the correct explanation of A.

    B) Both A and R are individually true and R is not the correct explanation of A.

    C) 'A' is true but 'R' is false

    D) 'A' is false but 'R' is true

    E) Both A and R are false.

    Correct Answer: A

    Solution :

    \[\frac{dy}{dx}=3{{x}^{2}}-2x-1\] At  \[(1,1),\left( \frac{dy}{dx} \right)=3\times {{(1)}^{2}}-2\times 1-1=3-2-1=0\] \[\Rightarrow \] Slope of tangent  \[=0\Rightarrow \]tangent is parallel to axis \[\Rightarrow \] Assertion [A] is true. Reason [R] is true and is correct explanation of A. Hence option [A] is the correct answer.


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