Tính $\underset{x\to \frac{\pi }{2}}{\mathop{\lim }}\,\frac{1+{{\sin }^{6}}x-5{{\cos }^{6}}x}{1+{{\sin }^{4}}x-{{\cos }^{4}}x}$ ?
A. $\underset{x\to \frac{\pi }{2}}{\mathop{\lim }}\,\frac{1+{{\sin }^{6}}x-5{{\cos }^{6}}x}{1+{{\sin }^{4}}x-{{\cos }^{4}}x}=0$.
B. $\underset{x\to \frac{\pi }{2}}{\mathop{\lim }}\,\frac{1+{{\sin }^{6}}x-5{{\cos }^{6}}x}{1+{{\sin }^{4}}x-{{\cos }^{4}}x}=-1$.
C. $\underset{x\to \frac{\pi }{2}}{\mathop{\lim }}\,\frac{1+{{\sin }^{6}}x-5{{\cos }^{6}}x}{1+{{\sin }^{4}}x-{{\cos }^{4}}x}=1$.
D. $\underset{x\to \frac{\pi }{2}}{\mathop{\lim }}\,\frac{1+{{\sin }^{6}}x-5{{\cos }^{6}}x}{1+{{\sin }^{4}}x-{{\cos }^{4}}x}=+\infty $.
Loga
Hóa Học lớp 12
