I try to use **walfram mathematica** to compute a double integral,
my code is 

    Integrate[0.5*exp[-90*(x - 0.5)^2 - 45*(y + 0.1)^4] + exp[-45*(x + 0.4)^2 - 60*(y - 0.5)^2], {x, -1, 1}, {y, -1, 1}]

while the output is just a simplify, not a result.
Then I try to use **walfram alpha online**, and it gives the anwser.
I'm really confused!

[![enter image description here][1]][1]


  [1]: https://i.sstatic.net/eAsZRobv.png