Question

Answer 1

\(=\dfrac{\sqrt{\left(m^2-4\right)}}{m-1}=\dfrac{\left|m^2-4\right|}{m-1}=\dfrac{\left|4-2\sqrt{3}-4\right|}{1-\sqrt{3}-1}=\dfrac{2\sqrt{3}}{-\sqrt{3}}=-2\)

Answer 2

`\frac{sqrt{m^4-8m^2+16}}{m-1}` (`m\ne1`)

`= \frac{sqrt{(m^2-4)^2}}{m-1}`

`= \frac{|m^2-4|}{m-1}`

Thay `m=1-sqrt3` (tm) vào biểu thức, ta được:

`\frac{|(1-sqrt3)^2-4|}{1-sqrt3-1}`

`= \frac{|1-2sqrt3+3-4|}{-sqrt3}`

`= \frac{|-2sqrt3|}{-sqrt3}`

`= \frac{2sqrt3}{-sqrt3}`

`= -2`