Question

Tìm x thuộc Q, biết

a) (x+2).(x-4) < 0

b) (x-3). (x+\(\frac{3}{4}\)) > 0

Answer 1

\(a.\left(x+2\right)\left(x-4\right)< 0\Leftrightarrow\orbr{\begin{cases}x+2< 0\\x-4< 0\end{cases}\Leftrightarrow\orbr{\begin{cases}x< -2\\x< 4\end{cases}}}\)

\(b.\left(x-3\right).\left(x+\frac{3}{4}\right)>0\Leftrightarrow\orbr{\begin{cases}x-3>0\\x+\frac{3}{4}>0\end{cases}\Leftrightarrow\orbr{\begin{cases}x>3\\x>-\frac{3}{4}\end{cases}}}\)

Answer 2

minh lam giong ban kia nha

k tui nha

thanks