[m]lim_{x → 0}\frac{x^4(\sqrt{1+xsinx}+\sqrt{1+xtgx})}{xsinx(1-\frac{1}{cosx})}=[/m]
[m]=lim_{x → 0}\frac{x^3(\sqrt{1+xsinx}+\sqrt{1+xtgx})}{sinx(\frac{cosx-1}{cosx})}=[/m]
[m]=lim_{x → 0}\frac{x^3(\sqrt{1+xsinx}+\sqrt{1+xtgx})}{sinx(\frac{-2sin^2\frac{x}{2}}{cosx})}=\frac{2}{(-\frac{2}{4})}=-4[/m]