Evaluate lim
- evaluate lim xu21920 sin4x/sin2x
- evaluate lim x approaches infinity
- evaluate lim xu21920 4x-2x^2/sinx
- evaluate lim xu21920 1-cosx/x
- evaluate lim xu21920 (tanx/x)^1/x^2
- evaluate lim xu21920 tanx-sinx/x^3
- evaluate lim xu21921 x15-1/x10-1
- evaluate lim xu21920 u221A1+x-1/x
- evaluate lim xu21920 sinx/x
- evaluate lim xu21920 1-cosx/x^2
