Let f(x, y)=x2ex2 and let r be the triangle bounded by the lines x=3, x=y/2, and y=x in the xy-plane. (a) express ∫rfda as a double integral in two different ways by filling in the values for the integrals below. (for one of these it will be necessary to write the double integral as a sum of two integrals, as indicated; for the other, it can be written as a single integral.)