MCQ
Lef $f:(0, \pi) \rightarrow R$ be a function given by

$f(x)=\left\{\begin{array}{cc}\left(\frac{8}{7}\right)^{\frac{\tan 8 x}{\tan 7 x}}, & 0 < x < \frac{\pi}{2} \\ a-8, & x=\frac{\pi}{2} \\ (1+\mid \cot x)^{\frac{b}{a}|\tan x|}, & \frac{\pi}{2} < x < \pi\end{array}\right.$

Where $a, b \in Z$. If $f$ is continuous at $x=\frac{\pi}{2}$, then $\mathrm{a}^2+\mathrm{b}^2$ is equal to ..........

  • A
    $12$
  • $81$
  • C
    $35$
  • D
    $74$

Answer

Correct option: B.
$81$
b
LHL at $\mathrm{x}=\frac{\pi}{2}$

$\lim _{x \rightarrow \frac{\pi}{2}}\left(\frac{8}{7}\right)^{\frac{\tan 8 x}{\tan 7 x}}=\left(\frac{8}{7}\right)^0=1$

$RHL$ at $\mathrm{x}=\frac{\pi}{2}$

$\lim _{x \rightarrow \frac{\pi}{2}}(1+|\cot x|)^{\frac{b}{a}|\tan x|}$

$=\mathrm{e}^{\left.\lim _{\left.\mathrm{x} \rightarrow \frac{\pi}{2} \right\rvert\, \cot x} \mathrm{~b}\left|\frac{\mathrm{b}}{\mathrm{a}}\right| \tan x \right\rvert\,}=\mathrm{e}^{\frac{\mathrm{b}}{\mathrm{a}}}$

$\Rightarrow 1=\mathrm{a}-8=\mathrm{e}^{\frac{\mathrm{b}}{\mathrm{a}}}$

$\Rightarrow \mathrm{a}=9, \mathrm{~b}=0$

$\Rightarrow a^2+b^2=81$

Need a full question paper?

Generate a complete, print-ready paper with questions like this in minutes — across 16+ boards, with answer keys.

Start Generating Free

Similar questions

Let $f (x) = \frac{{\sqrt {x\,\, - \,\,2\,\sqrt {x\,\, - \,\,1} } }}{{\sqrt {x\,\, - \,\,1} \,\, - \,\,1}}. x$ then :
Maximum value of $x{(1 - x)^2}$ when $0 \le x \le 2$, is
Two dice are thrown simultaneously. The probability of getting the sum $2$ or $8$ or $12$  is
The correct evaluation of $\int_0^\pi {\left| {\,{{\sin }^4}x\,} \right|\,dx} $ is
$(z + a)(\bar z + a)$, where $a$ is real, is equivalent to
The sum of coefficients in the expansion of ${(x + 2y + 3z)^8}$ is
Let $h(x) = f(x) - {(f(x))^2} + {(f(x))^3}$ for every real number $ x$ . Then
If $x$ satisfies the equation $\left( {\int\limits_0^1 {\frac{{dt}}{{{t^2} + 2t\cos \alpha  + 1}}} } \right)\,{x^2}$ $-$ $\,\left( {\int\limits_{ - 3}^3 {\frac{{{t^2}\sin 2t}}{{{t^2} + 1}}\,dt} } \right)\,x$ $-$ $2$  $ =$ $ 0 (0 < \alpha < \pi ), $ then the value $x$ is
A bag contains $5$ white, $7$ red and $8$ black balls. If four balls are drawn one by one without replacement, what is the probability that all are white
Match the statements in column-$I$ with those in column-$II$.

[Note: Here $z$ takes the values in the complex plane and $\operatorname{Im} z$ and $\operatorname{Re} z$ denote, respectively, the imaginary part and the real part of $z]$

column-$I$ column-$II$
$(A)$ The set of points $z$ satisfying $|z-i| z||=|z+i| z||$ is contained in or equal to $(p)$ an ellipse with eccentricity $\frac{4}{5}$
$(B)$ The set of points $z$ satisfying $|z+4|+|z-4|=10$ is contained in or equal to $(q)$ the set of points $z$ satisfying $\operatorname{Im} z=0$
$(C)$ If $|\omega|=2$, then the set of points $z=\omega-1 / \omega$ is contained in or equal to $(r)$ the set of points $z$ satisfying $|\operatorname{Im} z| \leq 1$
$(D)$ If $|\omega|=1$, then the set of points $z=\omega+1 / \omega$ is contained in or equal to $(s)$ the set of points $z$ satisfying $|\operatorname{Re} z| \leq 1$
  $(t)$ the set of points $z$ satisfying $|z| \leq 3$