Find the indicated limit by using the limits \[ \lim_{(x,y)\to(a,b)} f(x,y) = 5 \quad \text{and} \quad \lim_{(x,y)\to(a,b)} g(x,y) = -4. \] \[ \lim_{(x,y)\to(a,b)} [f(x,y) - g(x,y)] \] **Answer:** 9 1.解题 2.讲题 3.使用 MathTex 显示中文