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

$\int_{}^{} {{{\sin }^{ - 1}}x\;dx} $is equal to
Which of the following set of points are non- collinear
$\int\frac{\text{x}^3}{\sqrt{1+\text{x}^2}}\text{ dx}=\text{a}(1+\text{x}^2)^{\frac{3}{2}}+\text{b}\sqrt{1+\text{x}^2}+\text{C},$ then:
  1. $\text{a}=\frac{1}{3},\text{ b}=1$
  2. $\text{a}=-\frac{1}{3},\text{ b}=1$
  3. $\text{a}=-\frac{1}{3},\text{ b}=-1$
  4. $\text{a}=\frac{1}{3},\text{ b}=-1$
If $\vec{\text{a}}$ and $\vec{\text{b}}$ are unit vectors, then which of the following values of $\vec{\text{a}}.\vec{\text{b}}$ is not possible?
  1. $\sqrt{3}$
  2. $\frac{\sqrt{3}}{2}$
  3. $\frac{1}{\sqrt{2}}$
  4. $\frac{-1}{2}$
A force $(\overrightarrow F ) = 2i + j - k$ acts at a point  $A$, whose position vector is $2i - j$. The moment of $F$ about the origin is
If A and B are matrices of the same order, then ABT - BAT is a:
  1. Skew-symmetric matrix.
  2. Null matrix.
  3. Unit matrix.
  4. Symmetric matrix.
Using the factor theorem it is found that a + b, b + c and c + a are three factors of the determinant $\begin{vmatrix}-2\text{a}&\text{a}+\text{b}&\text{a}+\text{c}\\\text{b}+\text{a}&-2\text{b}&\text{b}+\text{c}\\\text{c}+\text{a}&\text{c}+\text{b}&-2\text{c}\end{vmatrix}$ the other factor in the value of the determinant is:
  1. 4
  2. 2
  3. a + b + c
  4. None of these.
$\tan \left[ {\frac{1}{2}{{\sin }^{ - 1}}\left( {\frac{{2a}}{{1 + {a^2}}}} \right) + \frac{1}{2}{{\cos }^{ - 1}}\left( {\frac{{1 - {a^2}}}{{1 + {a^2}}}} \right)} \right] = $
The area of the region $A\,\{ \,(x,y)\,\,:\,\,0\,\, \le \,y\, \le \,x\,\left| x \right|\, + \,1$ and $ - \,1\, \le \,x\, \le \,1\,\} $ in sq. units, is
Let $R$ be the set of real numbers and $f: R \rightarrow R$ be defined by $f(x)=\frac{\{x\}}{1+[x]^2}$, where $[x]$ is the greatest integer less than or equal to $x$, and $\left\{x{\}}=x-[x]\right.$. Which of the following statements are true?

$I.$ The range of $f$ is a closed interval.

$II.$ $f$ is continuous on $R$.

$III.$ $f$ is one-one on $R$