Question

giải BPT: 3(x-1)/(x+2)< 3

Answer 1

\(\dfrac{3\left(x-1\right)}{x+2}< 3\)

⇔ \(\dfrac{3x-3}{x+2}-3< 0\)

⇔ \(\dfrac{3x-3-3x-6}{x+2}< 0\)

⇔ \(\dfrac{-9}{x+2}\) < 0

Do : - 9 < 0

⇒ x + 2 > 0

⇒ x > - 2

KL.....

Answer 2

\(\dfrac{3\left(x+1\right)}{x+2}< 3\)

\(\Leftrightarrow\dfrac{3\left(x+1\right)}{x+2}-3< 0\)

\(\Leftrightarrow\dfrac{3x+3-3\left(x+2\right)}{x+2}< 0\)

\(\Leftrightarrow\dfrac{-3}{x+2}< 0\)

Vì -3 < 0

\(\Rightarrow x+2>0\)

\(\Leftrightarrow x>-2\)

Vậy BPT có nghiệm x > - 2