导数除法法则求导y'={x'*(4-x²)-x*[√(4-x²)]'}/[√(4-x²)]²={4-x²-2x²/[√(4-x²)]}/(4-x²)=1-2x²/[√(4-x²)*(4-x²)]注：√(4-x²)]是复合函数。y=√(4-x²)]的求导过程：令y=√u,u=4-x²y'=(√u)'*u'=u^(-1/2)*(-2x)=-2x/(√u)=-2x/[(√4-x²)]
