求limx→π/4(xtanx-1)
由xtanx=xsinx/cosx及limx→π/4sinx=sinπ/4=√2/2=limx→π/4cosx 并按四则运算法则有limx→π/4（xtanx-1) =limx→π/4xlimx→π/4sinx/limx→π/4cosx-limx→π/41=π/4-1
求limx→π/4(xtanx-1)
由xtanx=xsinx/cosx及limx→π/4sinx=sinπ/4=√2/2=limx→π/4cosx 并按四则运算法则有limx→π/4（xtanx-1) =limx→π/4xlimx→π/4sinx/limx→π/4cosx-limx→π/41=π/4-1
