Calculus 8th Edition

if the domain or range of the integrated portion approach infinity then it is an improper integral (a) the domain and range never approach infinity. this can be seen by graphing it (b) $\lim\limits_{x \to \pi/2}$ tan(x) = $\infty$ the range goes to $\infty$therefore B is improper.(optional:graph to double check.) (c) $\lim\limits_{a \to -1}$ = $\infty$ the range goes to $\infty$ therefore C is improper.(optional:graph to double check.) (d) the domain goes to $\infty$ therefore D is improper.(optional:graph to double check.)