Cho

Câu hỏi: Cho $y={\left(\frac{1}{4}\right)}^{1-x}$ Tính y'

A. $y\text{'}=\left(\frac{1}{4}\right).\ln \frac{1}{4}$

B. $y\text{'}={\frac{\left({\displaystyle \frac{1}{4}}\right)}{\ln 4}}^{1-x}$

C. $y\text{'}=4^{x-1}.\ln 4$

D. $y\text{'}={\left(\frac{1}{4}\right)}^{1-x}.\ln \frac{1}{4}$