1)

If $\int\frac{1}{\sqrt{9-16x^{2}}}dx=\alpha \sin^{-1}(\beta x)+c $  then $\alpha+\frac{1}{\beta}$=


A) 1

B) $\frac{7}{12}$

C) $\frac{19}{12}$

D) $\frac{9}{12}$

Answer:

Option A

Explanation:

Let l= $\int\frac{1}{\sqrt{9-16x^{2}}}dx$

 =$\int\frac{1}{\sqrt{(3)^2-(4x)^{2}}}dx=\frac{1}{4}\frac{1}{\sqrt{(\frac{3}{4})^{2}-(x)^{2}}}dx$

=  $\frac{1}{4}\sin^{-1}\frac{4x}{3}+C$

                          $\left[\because \int \frac{1}{\sqrt{a^{2}-x^{2}}} dx=\sin^{-1}\frac{x}{a}+C\right]$

 But , it is given that

 $\int\frac{1}{\sqrt{9-16x^{2}}}dx=\alpha \sin ^{-1}(\beta x)+C$

$\therefore$   $\alpha \sin ^{-1}(\beta x)+C=\frac{1}{4}\sin^{-1}(\frac{4}{3}x)+C$

On comparing both sides, we get

 $\alpha =\frac{1}{4}$  and  $\beta =\frac{4}{3}$

 $\therefore$      $\alpha+\frac{1}{\beta} =\frac{1}{4}+\frac{1}{4}=\frac{1}{4}+\frac{3}{4}=1$