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KCET · Maths · Definite Integration

\( f(x)=\left\{\begin{array}{cl}3 x-8 & \text { if } x \leq 5 \\ 2 k & \text { if } x>5\end{array}\right. \) is continuous, find \( k . \)

  1. A \( \frac{2}{7} \)
  2. B \( \frac{3}{7} \)
  3. C \( \frac{4}{7} \)
  4. D \( \frac{7}{2} \)
Verified Solution

Answer & Solution

Correct Answer

(D) \( \frac{7}{2} \)

Step-by-step Solution

Detailed explanation

Given that, \(f(x)=\left\{\begin{array}{cc}3 x-8 & x \leq 5 \\ 2 k & x>5\end{array}\right.\)
At \(x=5\), we have \(f(5)=3(5)-8=7\)
Taking R.H.L, we have
\(\lim _{x \rightarrow 5} 2 k=2 k\)
\(\mathrm{WE}\) know that for continuous L.H.L \(=\) R.H.L.
Therefore, \(7=2 k \Rightarrow k=\frac{7}{2}\)