MCQ
A continuously differentiable function $\phi (x)\,{\rm{in}}\,(0,\,\pi )$ satisfying $y' = 1 + {y^2},\,\,y(0) = 0 = y(\pi )$ is
- A$\tan x$
- B$x(x - \pi )$
- C$(x - \pi )$ $(1 - {e^x})$
- ✓Not possible
Integrating both sides,
$\int {\frac{{dy}}{{1 + {y^2}}} = \int {dx} } $ ==> ${\tan ^{ - 1}}y = x + c$
At $x = 0,$$y = 0,$ then $c = 0$
At $x = \pi ,$$y = 0,$ then ${\tan ^{ - 1}}0 = \pi + c$ ==> $c = - \pi $
$\therefore {\tan ^{ - 1}}y = x$==>$y = \tan x = \phi (x)$
Therefore, solution is $y = \tan x$
But $\tan x$ is not continuous function in $(0,\,\pi )$
Hence, $\phi \,(x)$ is not possible in $(0,\,\pi )$.
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$\mathrm{Q}=\mathrm{A}^{\mathrm{T}} \mathrm{BA}$, then the inverse of the matrix $\mathrm{A} \mathrm{Q}^{2021} \mathrm{~A}^{\mathrm{T}}$ is equal to :