MCQ
The value of $p$ and $q$ for which the function
$f(x)=\left\{\begin{array}{ll}\frac{\sin (p+1) x+\sin x}{x}, & x<0 \\q, & x=0 \\\frac{\sqrt{x+x^2}-\sqrt{x}}{x^{3 / 2}}, & x>0\end{array}\right.$
is continuous for all x in R, are
  • A
    $p=\frac{1}{2}, q=-\frac{3}{2}$
  • B
    $p=\frac{5}{2}, q=\frac{1}{2}$
  • $p=-\frac{3}{2}, q=\frac{1}{2}$
  • D
    $p=\frac{1}{2}, q=\frac{1}{2}$

Answer

Correct option: C.
$p=-\frac{3}{2}, q=\frac{1}{2}$
(C)
Since $f (x)$ is continuous for all $x$ in R .
$\therefore f (x)$ is continuous at $x=0$.
$\therefore \quad f(0)=\lim _{x \rightarrow 0^{-}} f(x)$
$\Rightarrow q =\lim _{x \rightarrow 0} \frac{\sin ( p +1) x+\sin x}{x}$
$\Rightarrow q =\lim _{x \rightarrow 0}\left[( p +1) \times \frac{\sin ( p +1) x}{( p +1) x}+\frac{\sin x}{x}\right]$
$\Rightarrow q =( p +1)+1$
$\Rightarrow q=p+2$
The values of $p$ and $q$ in option (C) satisfies this condition.

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