JEE MAIN - Mathematics (2022 - 28th July Evening Shift - No. 10)
The area enclosed by the curves $$y=\log _{e}\left(x+\mathrm{e}^{2}\right), x=\log _{e}\left(\frac{2}{y}\right)$$ and $$x=\log _{\mathrm{e}} 2$$, above the line $$y=1$$ is:
$$2+\mathrm{e}-\log _{\mathrm{e}} 2$$
$$1+e-\log _{e} 2$$
$$e-\log _{e} 2$$
$$1+\log _{e} 2$$
Explanation
_28th_July_Evening_Shift_en_10_1.png)
According to NTA, the required region $A_2$ which is shaded in crossed lines and comes out to be
$$ A_2=\int_1^2\left(\ln \frac{2}{y}-e^y+e^2\right) d y=1+e-\ln 2 $$
But according to us the required region $A_1$ comes out to be shaded in parallel lines, which can be obtained as
$$ \begin{aligned} A_1 &=\int_0^{\ln 2}\left(\ln \left(x+e^2\right)-2 e^{-x}\right) d x \\\\ &=\left.\left\{\left(x+e^2\right) \ln \left(x+e^2\right)-x+2 e^{-x}\right\}\right|_0 ^{\ln 2} \\\\ &=\left(\ln 2+e^2\right) \ln \left(\ln 2+e^2\right)-\ln 2+1 \\\\ & \quad-2 e^2-2 \\\\ &=\left(\ln 2+e^2\right) \ln \left(\ln 2+e^2\right)-\ln 2-2 e^2-1 \end{aligned} $$
Not given in any option.
The region asked in the question is bounded by three curves
$$ \begin{aligned} &y=\ln \left(x+e^2\right) \\\\ &x=\ln \left(\frac{2}{y}\right) \\\\ &x=\ln 2 \end{aligned} $$
There is only one region which satisfies above requirement and which also lies above line $y=1$
Line $y=1$ may or may not be the boundary of the region.
Comments (0)
