find integral exp(-x)x^-2
If you mean 1/x^2 e^-x dx, there is no integral using elementary functions.
Maybe I misread it.
http://www.wolframalpha.com/input/?i=integral+1%2Fx^2+e^-x+dx
Maybe I misread it.
http://www.wolframalpha.com/input/?i=integral+1%2Fx^2+e^-x+dx