Let $f$ be the function defined by $f\left(x\right)=\frac{6}{1+x^2}$. Which of the following is the domain of $f$?

Evaluate the vector integral from $t=0$ to $t=4$ of the vector function $sec\left(t\right)tan\left(t\right)\mathbf{i}+tcos\left(2t\right)\mathbf{j}+{sin}^2\left(2t\right)cos\left(2t\right)\mathbf{k}$ with respect to $t$.

Given the power series $\sum \underset{n=1}{}\stackrel{\infty }{}\frac{{(}^{-1}n}{x^n}/9^n$, find the radius of convergence, $r$, of the series.

Evaluate the triple integral of $1$ over the part of the ball defined by $x^2+y^2+z^2\le 8$ that lies in the first octant.

Evaluate the triple integral ${\int }_{}^{}{\int }_{}^{}{\int }_{}^{}z{d}_V$, where E is the region bounded by the parabolic cylinder $y=x^2$, the planes $z=0$, $z=4$, and $y=4$.

Evaluate the integral: ${\int }_{x=1}^{x=2}2x(x^2+4x+20) dx$.

Given the boundary-value problem $y^{″}-2y^{\prime }+2y=2x-2$, with $y\left(0\right)=0$ and $y\left(\pi \right)=\pi$, which of the following is the correct solution for $y\left(x\right)$?

Which of the following is a power series representation for the function $f\left(x\right)=x^4\arctan \left(x^3\right)$ centered at $x=0$?

Which of the following is a power series representation for the function $f\left(x\right)=x^8\arctan \left(x^3\right)$ centered at $x=0$?