数学作业题目在附件中，谢谢！
题目在附件中，谢谢！
解:2.f(x,y+h)=x^2-2x(y+h)+3(y+h)^2 f(x,y+h)-f(x,y) =x^2-2x(y+h)+3(y+h)^2-(x^2-2xy+3y^2) =x^2-2xy-2xh+3y^2+6hy+3h^2-x^2+2xy-3y^2 =-2xh+6hy+3h^2 [f(x,y+h)-f(x,y)]/h =(-2xh+6hy+3h^2)/h =-2x+6y+3h