∫∫e^(-y^2)dxdy =∫(0,1)dy∫(0,y)e^(-y^2)dx =∫(0,1)ye^(-y^2)dy =(-1/2)∫(0,1)e^(-y^2)d(-y^2) =(-1/2)e^(-y^2)|(0,1) =(-1/2)(1/e-1) =(1/2)(1-1/e)
