## tìm x, thỏa mãn: a, (2x-3).(x-1)>0 b, (3x+1).(x-2)<0 mng mn giải giúp mk ạ.......!

Question

tìm x, thỏa mãn:
a, (2x-3).(x-1)>0
b, (3x+1).(x-2)<0 mng mn giải giúp mk ạ.......!

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3 tuần 2021-08-21T17:04:22+00:00 2 Answers 0 views 0

1. Giải thích các bước giải:

a) (2x-3)(x-1)>0

=>2x-3;x-1 cùng dấu

=>$$\left[ \begin{array}{l}\left\{\begin{matrix}2x-3>0\\x-1>0\end{matrix}\right.\\\left\{\begin{matrix}2x-3<0\\x-1<0\end{matrix}\right.\end{array} \right.$$ =>$$\left[ \begin{array}{l}\left\{\begin{matrix}2x>3\\x>1\end{matrix}\right.\\\left\{\begin{matrix}2x<3\\x<1\end{matrix}\right.\end{array} \right.$$=>$$\left[ \begin{array}{l}\left\{\begin{matrix}x>\dfrac{3}{2}\\x>1\end{matrix}\right.\\\left\{\begin{matrix}x<\dfrac{3}{2}\\x<1\end{matrix}\right.\end{array} \right.$$=>$$\left[ \begin{array}{l}x>\dfrac{3}{2}\\x<1\end{array} \right.$$

Vậy x>3/2 hoặc x<1.

b) (3x+1).(x-2)<0

=>3x+1;x-2 trái dấu

=>$$\left[ \begin{array}{l}\left\{\begin{matrix}3x+1>0\\x-2<0\end{matrix}\right.\\\left\{\begin{matrix}3x+1<0\\x-2>0\end{matrix}\right.\end{array} \right.$$ =>$$\left[ \begin{array}{l}\left\{\begin{matrix}3x>-1\\x<2\end{matrix}\right.\\\left\{\begin{matrix}3x<-1\\x>2\end{matrix}\right.\end{array} \right.$$

=>$$\left[ \begin{array}{l}\left\{\begin{matrix}x>-\dfrac{1}{3}\\x<2\end{matrix}\right.\\\left\{\begin{matrix}x<-\dfrac{1}{3}\\x>2\end{matrix}\right.\text{(loại)}\end{array} \right.$$=>-1/3<x<2

Vậy -1/3<x<2.

2. Đáp án:

Giải thích các bước giải:

Mk gửi ảnh r đó