Maths > Differentiation > 8.0 Matrix Differentiation

  Differentiation
    1.0 Differentiation
    2.0 Some Basic Differentiation formulae
    3.0 Properties of Differentiation
    4.0 Derivative of Common Functions
    5.0 Explicit and Implicit form:
    6.0 Parametric Differentiation
    7.0 Differentiation of one function w.r.t other
    8.0 Matrix Differentiation
    9.0 Logarathimic Differentiation
    10.0 Differentiation using substitution

8.1 Differentiation of determinant matrix

If, \[y = \left| {\begin{array}{c} {{a_{11}}}&{{a_{12}}}&{{a_{13}}} \\ {{a_{21}}}&{{a_{22}}}&{{a_{23}}} \\ {{a_{31}}}&{{a_{32}}}&{{a_{33}}} \end{array}} \right|\]

then, \[y = \left| {\begin{array}{c} {a{'_{11}}}&{a{'_{12}}}&{a{'_{13}}} \\ {{a_{21}}}&{{a_{22}}}&{{a_{23}}} \\ {{a_{31}}}&{{a_{32}}}&{{a_{33}}} \end{array}} \right| + \left| {\begin{array}{c} {{a_{11}}}&{{a_{12}}}&{{a_{13}}} \\ {a{'_{21}}}&{a{'_{22}}}&{a{'_{23}}} \\ {{a_{31}}}&{{a_{32}}}&{{a_{33}}} \end{array}} \right| + \left| {\begin{array}{c} {{a_{11}}}&{{a_{12}}}&{{a_{13}}} \\ {{a_{21}}}&{{a_{22}}}&{{a_{23}}} \\ {a{'_{31}}}&{a{'_{32}}}&{a{'_{33}}} \end{array}} \right|\]


Question 1: Find derivative of \[y = \left| {\begin{array}{c} {{x^2}}&{{x^3}}&x \\ {{e^x}}&{\log x}&{{2^x}} \\ {\cos x}&{\sinh x}&{{{\tan }^{ - 1}}x} \end{array}} \right|\]

Solution: \[y = \left| {\begin{array}{c} {{x^2}}&{{x^3}}&x \\ {{e^x}}&{\log x}&{{2^x}} \\ {\cos x}&{\sinh x}&{{{\tan }^{ - 1}}x} \end{array}} \right|\]

\[\frac{{dy}}{{dx}} = \left| {\begin{array}{c} {\frac{d}{{dx}}{x^2}}&{\frac{d}{{dx}}{x^3}}&{\frac{d}{{dx}}x} \\ {{e^x}}&{\log x}&{{2^x}} \\ {\cos x}&{\sinh x}&{{{\tan }^{ - 1}}x} \end{array}} \right| + \left| {\begin{array}{c} {{x^2}}&{{x^3}}&x \\ {\frac{d}{{dx}}{e^x}}&{\frac{d}{{dx}}\log x}&{\frac{d}{{dx}}{2^x}} \\ {\cos x}&{\sinh x}&{{{\tan }^{ - 1}}x} \end{array}} \right| + \left| {\begin{array}{c} {{x^2}}&{{x^3}}&x \\ {{e^x}}&{\log x}&{{2^x}} \\ {\frac{d}{{dx}}\cos x}&{\frac{d}{{dx}}\sinh x}&{\frac{d}{{dx}}{{\tan }^{ - 1}}x} \end{array}} \right|\]

We know that, $$\frac{d}{dx}x^n = nx^{n-1}$$$$ \frac{d}{{dx}}{e^x} = {e^x} $$$$ \frac{d}{{dx}}\cos x = - \sin x $$$$ \frac{d}{{dx}}{\tan ^{ - 1}}x = \frac{1}{{1 + {x^2}}} $$$$ \frac{d}{{dx}}{a^x} = {a^x}\log a $$$$ \frac{d}{{dx}}{\log _e}x = \frac{1}{{x\ln e}} = \frac{1}{x} $$$$ \frac{d}{{dx}}\sinh x = \cosh x $$


\[\frac{{dy}}{{dx}} = \left| {\begin{array}{c} {2{x^{2 - 1}}}&{3{x^{3 - 1}}}&{1{x^{1 - 1}}} \\ {{e^x}}&{\log x}&{{2^x}} \\ {\cos x}&{\sinh x}&{{{\tan }^{ - 1}}x} \end{array}} \right| + \left| {\begin{array}{c} {{x^2}}&{{x^3}}&x \\ {{e^x}}&{\log x}&{{2^x}\log 2} \\ {\cos x}&{\sinh x}&{{{\tan }^{ - 1}}x} \end{array}} \right| + \left| {\begin{array}{c} {{x^2}}&{{x^3}}&x \\ {{e^x}}&{\log x}&{{2^x}} \\ { - \sin x}&{\cosh x}&{\frac{1}{{1 + {x^2}}}} \end{array}} \right|\]

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