An improper double integral can often be computed similarly to an improper integral of one variable. the first iteration of the following improper integral is conducted just as if it were a proper integral. one then evaluates an improper integral of a single variable by taking appropriate limits. evaluate the following improper integral as an iterated integral. integrate infinity ? infinity integrate infinity ? infinity 1/(x^2+16)(y^2+4) dx dy integrate infinity ? infinity integrate infinity ? infinity 1/(x^2+16)(y^2+4) dx dy =