I recently purchased the TI-Nspire CX CAS, and when performing certain integrals it seems to spit out an answer still containing variables. For example, when my input is:
$$\int_0^1 \int_0^1 xe^{-(x+xy)} \, dy \, dx$$
the calculator gives the result as:
$$e^{-xy}(1-2e^{-1})$$
Similarly, if I input only the inner integral, I get:
$$\int_0^1 xe^{-(x+xy)} \, dy = xe^{-x-xy}$$
Does anyone know what might be causing this behavior? Wolfram Alpha doesn't have an issue with this integral. Thanks!