cosθ=a*b/|a||b|=-1/(√3√5)=-1/√15m*n=2k+4,k=-23/√6e^(sin(xy))*cos(xy)*(xdy+ydx)fx=yx^(y-1),fxy=x^(y-1)+yx^(y-1)lnx积分换序∫ye^(-y²)dy=1/2e^(-y²)=1/2(1-e^(-4))(1)不收敛2
cosθ=a*b/|a||b|=-1/(√3√5)=-1/√15m*n=2k+4,k=-23/√6e^(sin(xy))*cos(xy)*(xdy+ydx)fx=yx^(y-1),fxy=x^(y-1)+yx^(y-1)lnx积分换序∫ye^(-y²)dy=1/2e^(-y²)=1/2(1-e^(-4))(1)不收敛2