微积分设f(x,y)=(x²+4y²)/(x+y),(x,y)≠(0,0),求f'y(0,0)

来源：学生作业帮助网编辑：作业帮时间：2024/06/03 10:17:50

f'y(0,0)=lim{Δy->0} [f(0,0+Δy)-f(0,0)] / Δy
=lim{Δy->0} (4Δy-0)/Δy
=4

微积分 设f(x,y)=(x²+4y²)/(x+y),(x,y)≠(0,0),求f'y(0,0)