मराठी

If F ( X ) = { Log ( 1 + a X ) − Log ( 1 − B X ) X , X ≠ 0 K , X = 0 and F (X) is Continuous at X = 0, Then the Value of K is (A) a − B (B) a + B (C) Log a + Log B (D) None of These

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प्रश्न

If  \[f\left( x \right) = \begin{cases}\frac{\log\left( 1 + ax \right) - \log\left( 1 - bx \right)}{x}, & x \neq 0 \\ k , & x = 0\end{cases}\] and f (x) is continuous at x = 0, then the value of k is

पर्याय

  • a − 

  • a + b

  • log a + log 

  • none of these

MCQ
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उत्तर

\[a + b\]

 Given:

\[f\left( x \right) = \binom{\frac{\log\left( 1 + ax \right) - \log\left( 1 - bx \right)}{x}, x \neq 0}{k, x = 0}\]

If f(x) is continuous at x = 0, then

\[\lim_{x \to 0} f\left( x \right) = f\left( 0 \right)\]

\[\Rightarrow \lim_{x \to 0} \left( \frac{\log\left( 1 + ax \right) - \log\left( 1 - bx \right)}{x} \right) = k\]

\[\Rightarrow \lim_{x \to 0} \left( \frac{a\log\left( 1 + ax \right)}{ax} - \frac{b\log\left( 1 - bx \right)}{bx} \right) = k\]

\[ \Rightarrow a \lim_{x \to 0} \left( \frac{\log\left( 1 + ax \right)}{ax} \right) - b \lim_{x \to 0} \left( \frac{\log\left( 1 - bx \right)}{bx} \right) = k\]

\[ \Rightarrow a \lim_{x \to 0} \left( \frac{\log\left( 1 + ax \right)}{ax} \right) + b \lim_{x \to 0} \left( \frac{\log\left( 1 - bx \right)}{- bx} \right) = k\]

\[ \Rightarrow a \times 1 + b \times 1 = k \left[ \because \lim_{x \to 0} \frac{\log\left( 1 + x \right)}{x} = 1 \right]\]

\[ \Rightarrow k = a + b\]

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पाठ 8: Continuity - Exercise 9.4 [पृष्ठ ४३]

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आर.डी. शर्मा Mathematics Volume 1 and 2 [English] Class 12
पाठ 8 Continuity
Exercise 9.4 | Q 8 | पृष्ठ ४३

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