Question

Bài 1:Tìm xeQ:

a)(-3).(x+2) <0

b)(x-1).(x+\(\dfrac{1}{3}\)) >0

Answer 1

a) (-3).(x+2)<0

=>x+2>0

=>x> -2

b)(x-1).(x+\(\dfrac{1}{3}\))>0

<=>(x-1) và \(\left(x+\dfrac{1}{3}\right)\) cùng dấu

TH1: x-1 <0

và x+\(\dfrac{1}{3}\)<0

\(\left\{{}\begin{matrix}x< 1\\x< \dfrac{-1}{3}\end{matrix}\right.\) =>x<\(\dfrac{-1}{3}\)

TH2:x-1>0

và x+\(\dfrac{1}{3}\)>0

\(\left\{{}\begin{matrix}x>1\\x>\dfrac{-1}{3}\end{matrix}\right.\)=>x>1

Answer 2

a)(-3).(x+2) <0

=> x+2> 0

=> x>2

b)(x-1).(x+\(\dfrac{1}{3}\)) >0

=> x-1>0 hay x+\(\dfrac{1}{3}\) >0

=> x>1hay x>-\(\dfrac{1}{3}\)