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Question

Consider the function $G(x, y, z) = 0$. This function allows us to implicitly define each of three variables as a function of the other two variables. Assume that all partial derivatives of the function $G(x, y, z)$ exist everywhere. Then, the value of $\left(\frac{\partial z}{\partial x} \times \frac{\partial x}{\partial y} \times \frac{\partial y}{\partial z}\right)$ is _________ (in integer)

Implicit Differentiation and Partial Derivatives

We are given an implicit function $G(x, y, z) = 0$. We need to find the value of the product $\left(\frac{\partial z}{\partial x} \times \frac{\partial x}{\partial y} \times \frac{\partial y}{\partial z}\right)$. We assume $G$'s partial derivatives exist and are non-zero where needed.

Finding Partial Derivatives

Using the rules of implicit differentiation:

  • To find $\frac{\partial z}{\partial x}$, we treat $y$ as a constant and differentiate $G$ with respect to $x$, considering $z$ as a function of $x$ and $y$:

    $ \frac{\partial G}{\partial x} + \frac{\partial G}{\partial z} \frac{\partial z}{\partial x} = 0 $

    Solving for $\frac{\partial z}{\partial x}$ yields:

    $ \frac{\partial z}{\partial x} = -\frac{\frac{\partial G}{\partial x}}{\frac{\partial G}{\partial z}} $

  • To find $\frac{\partial x}{\partial y}$, we treat $z$ as a constant and differentiate $G$ with respect to $y$, considering $x$ as a function of $y$ and $z$:

    $ \frac{\partial G}{\partial y} + \frac{\partial G}{\partial x} \frac{\partial x}{\partial y} = 0 $

    Solving for $\frac{\partial x}{\partial y}$ yields:

    $ \frac{\partial x}{\partial y} = -\frac{\frac{\partial G}{\partial y}}{\frac{\partial G}{\partial x}} $

  • To find $\frac{\partial y}{\partial z}$, we treat $x$ as a constant and differentiate $G$ with respect to $z$, considering $y$ as a function of $x$ and $z$:

    $ \frac{\partial G}{\partial z} + \frac{\partial G}{\partial y} \frac{\partial y}{\partial z} = 0 $

    Solving for $\frac{\partial y}{\partial z}$ yields:

    $ \frac{\partial y}{\partial z} = -\frac{\frac{\partial G}{\partial z}}{\frac{\partial G}{\partial y}} $

Calculating the Product

Now, we multiply these three partial derivatives:

$ \left(\frac{\partial z}{\partial x} \times \frac{\partial x}{\partial y} \times \frac{\partial y}{\partial z}\right) = \left(-\frac{\frac{\partial G}{\partial x}}{\frac{\partial G}{\partial z}}\right) \times \left(-\frac{\frac{\partial G}{\partial y}}{\frac{\partial G}{\partial x}}\right) \times \left(-\frac{\frac{\partial G}{\partial z}}{\frac{\partial G}{\partial y}}\right) $

Simplify the expression by cancelling terms:

$ = (-1) \times (-1) \times (-1) \times \left(\frac{\frac{\partial G}{\partial x}}{\frac{\partial G}{\partial x}}\right) \times \left(\frac{\frac{\partial G}{\partial y}}{\frac{\partial G}{\partial y}}\right) \times \left(\frac{\frac{\partial G}{\partial z}}{\frac{\partial G}{\partial z}}\right) $

$ = (-1) \times 1 \times 1 \times 1 $

$ = -1 $

Final Result

The value of the product $\left(\frac{\partial z}{\partial x} \times \frac{\partial x}{\partial y} \times \frac{\partial y}{\partial z}\right)$ is -1.

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Important Questions from Numerical Computation

  1. In an engineering college of 10,000 students, 1,500 like neither their core branches nor other branches. The number of students who like their core branches is 1/4th of the number of students who like other branches. The number of students who like both their core and other branches is 500.
    The number of students who like their core branches is

  2. $A$ is an ($n \times n$) matrix. Consider the following two statements 

    Statement 1: Columns of matrix $A$ are linearly independent 

    Statement 2: Inverse of matrix $A$ exists 

    Which one of the following statements is TRUE?

  3. Levenshtein distance is used to measure the minimum edit distance between two strings by counting the minimum number of editing operations (such as, insertions, deletions, substitutions) required to transform one string to another. Consider an alternative version of the Levenshtein distance in which each insertion and each deletion has a cost of 1 and substitutions are not allowed.

    Based on this alternative version, the Levenshtein distance between the strings, word and work is ______ (Answer in integer).
  4. In a given collection of documents, let $N$ be the total number of documents and let $d$ be the number of documents in which the term $t$ occurs.

    Which ONE of the following fractions is used to define the inverse document frequency (idf) of the term $t$?
  5. The total number of unique character bigrams in the string thoughtsoftheghosts (which contains 19 characters) is ______.
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