Question

Find all the values of x in the set of complex numbers that satisfy the following equation:

Answer 1

Compute all the component integrals first:

$I_1=\displaystyle\int_0^{\pi/4}2\sec x\,\mathrm dx=2\ln(\sqrt2+1)$
$I_2=\displaystyle\int_0^2\ln x\,\mathrm dx=2(\ln2-1)$
$I_3=\displaystyle\lim_{a\to\infty}\int_{-a}^a\frac{\mathrm dx}{x^2+1}=\pi$

Now,

$\sqrt2\approx1.4\implies \sqrt2+1\approx2.4$
$\implies \left\lceil I_1\right\rceil=2$

$e$
$\implies\left\lfloor I_2\right\rfloor=-1$

$\pi\approx3.14\implies\left\lceil I_3\right\rceil=4$

So the given equation reduces to

$\displaystyle\sum_{k=-1}^2\frac{\mathrm d}{\mathrm dx}x^{k+2}=1-4!$
$\dfrac{\mathrm dx}{\mathrm dx}+\dfrac{\mathrm dx^2}{\mathrm dx}+\dfrac{\mathrm dx^3}{\mathrm dx}+\dfrac{\mathrm dx^4}{\mathrm dx}=-23$
$4x^3+3x^2+2x+24=0$

a fairly standard cubic. Incidentally, when $x=-2$, the LHS reduces to 0, so $x+2$ is a factor of the cubic. You can find the remaining two solutions easily with the quadratic formula.