( 𝑥 − 1 ) ( 𝑥 − 2 ) < 0 ${\displaystyle \left(x-1\right)\left(x-2\right)<0}$

𝑥 − 1 𝑥 − 2 > 0 ${\displaystyle \frac{x-1}{x-2}>0}$

( 𝑥 − 1 ) 2 ( 𝑥 − 2 ) < 0 ${\displaystyle {\left(x-1\right)}^2\left(x-2\right)<0}$

( 𝑥 − 2 ) 2 𝑥 − 1 > 0 $\frac{{\left(x-2\right)}^2}{x-1_{}}>0$

1 < 𝑥 < 2 ${\displaystyle 1<x<2}$

1 < 𝑥 < 2 ${\displaystyle 1<x<2}$ или 𝑥 > 2 ${\displaystyle x>2}$

𝑥 < 1 ${\displaystyle x<1}$ или 1 < 𝑥 < 2 ${\displaystyle 1<x<2}$

𝑥 < 1 ${\displaystyle x<1}$ или 𝑥 > 2 ${\displaystyle x>2}$