Question
Let [•] denote the greatest integer function. If $\int_0^{ e ^3}\left[\frac{1}{ e ^{ x -1}}\right] dx =\alpha-\log _{ e } 2$, then $\alpha^3$ is equal to __________.

Answer

(8)
Explanation: $f(x)=\frac{1}{e^{x-1}}=e^{1-x}$
$f(x)=2$ / $f(x)=1$
$\frac{1}{ e ^{ x -1}}=2$ / $x=1$
$x=1-\ln 2$
$f(0)=e^1=2.71$
$f\left(e^3\right)=e^{1-e^3} \in(0,1)$
$I =\int_0^{1-\ell n 2} 2 dx +\int_{1-\ell n 2}^1 1 dx +\int_1^{ e ^3} 0 dx$
$=2(1-\ell n 2-0)+1(1-1+\ell n 2)+0$
$\alpha-\ell n 2=2-\ell n 2$
$\alpha=2$
$\alpha^3=8$

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

The minimum value of $9{\tan ^2}\theta + 4{\cot ^2}\theta $ is
Let $\mathrm{A}(1,0), \mathrm{B}(6,2)$ and $\mathrm{C}\left(\frac{3}{2}, 6\right)$ be the vertices of a triangle $ABC$. If $P$ is a point inside the triangle $\mathrm{ABC}$ such that the triangles $\mathrm{APC}, \mathrm{APB}$ and $BPC$ have equal areas, then the length of the line segment $PQ,$ where $Q$ is the point $\left(-\frac{7}{6},-\frac{1}{3}\right)$ is
If $2x,\;x + 8,\;3x + 1$ are in $A.P.$, then the value of $x$ will be
If $cosA + cosB = cosC,\ sinA + sinB = sinC$ then the value of expression $\frac{{\sin \left( {A + B} \right)}}{{\sin 2C}}$ is
Let $N$ be the sum of the numbers appeared when two fair dice are rolled and let the probability that $N -2, \sqrt{3 N }, N +2$ are in geometric progression be $\frac{ k }{48}$. Then the value of $k$ is
In the expansion of $(1+x)\left(1-x^2\right)\left(1+\frac{3}{x}+\frac{3}{x^2}+\frac{1}{x^3}\right)^5, x \neq 0$, the sum of the coefficient of $x^3$ and $x^{-13}$ is equal to
A line with direction ratios $2,1,2$ meets the lines $x=y+2=z$ and $x+2=2 y=2 z$ respectively at the point $P$ and $Q$. if the length of the perpendicular from the point $(1,2,12)$ to the line $\mathrm{PQ}$ is $l$, then $l^2$ is
$\int\limits_2^4 {\,\,\left[ {{{\log }_x}\,2\,\, - \,\,\frac{{{{\left( {{{\log }_x}\,2} \right)}^2}}}{{\ell n\,2}}} \right]} $ $dx =$
If  ${\log _5}2,\,{\log _5}({2^x} - 3)$ and  ${\log _5}(\frac{{17}}{2} + {2^{x - 1}})$ are in $A.P.$ then the value of $x$ is :-
The number of $5 -$tuples $(a, b, c, d, e)$ of positive integers such that

$I.$ $a, b, c, d, e$ are the measures of angles of a convex pentagon in degrees

$II$. $a \leq b \leq c \leq d \leq e$

$III.$ $a, b, c, d, e$ are in arithmetic progression is