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Need solution for RD Sharma Maths Class 12 Chapter 18 Continuity Excercise 8.1 Question 36 Subquestion (vi)

Answers (1)

Answer:

                k=10

Hint:

f\left ( x \right )  must be defined. The limit of the f\left ( x \right ) approaches the value x must exist.

Given:

                f(x)=\left(\begin{array}{cc} \frac{x^{2}-25}{x-5} & , x \neq 5 \\\\ k & , x=5 \end{array}\right)

Solution:

                f(x)=\left(\begin{array}{cc} \frac{x^{2}-25}{x-5} & , x \neq 5 \\\\ k & , x=5 \end{array}\right)

                f(x)=\left(\begin{array}{cc} \frac{(x-5)(x+5)}{x-5} \\\\ k, x=5 \end{array}, x \neq 5\right)                                  \left[\because a^{2}-b^{2}=(a+b)(a-b)\right]

                f(x)=\left(\begin{array}{cc} (x+5), & x \neq 5 \\\\ k & , x=5 \end{array}\right)

If f\left ( x \right ) is continuous at x=5 , then

                \begin{aligned} &\lim _{x \rightarrow 5} f(x)=f(5) \\ &\lim _{x \rightarrow 5}(x+5)=k \\ &k=5+5=10 \\ &k=10 \end{aligned}

               

               

               

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