N=(x-y)/(x+y)
分別對x,y求偏導數
其實求偏導數跟求導數是一樣的,只不過以前學得是一元的求導,現在是二元求導
如果對x求偏導數,那麼你就將y當作常數就行了
則有:
aN/ax(這裏a是偏導數負號)
=[1*(x+y)-(x-y)]/(x+y)^2
=2y/(x+y)^2
同理對y求偏導數也一樣
aN/ay
=[-(x+y)-(x-y)]/(x+y)^2
=-2x/(x+y)^2