Question

10,15,17 giúp với ạ

Answer 1

10) \(-2x^2+3x+2\ge0\)

\(\Leftrightarrow-2x^2+4x-x+2\ge0\)

\(\Leftrightarrow-2x\left(x-2\right)-\left(x-2\right)\ge0\)

\(\Leftrightarrow-\left(2x+1\right)\left(x-2\right)\ge0\)

\(\Leftrightarrow\left(2x+1\right)\left(x-2\right)\le0\)

\(\Rightarrow-\dfrac{1}{2}\le x\le2\)

15) \(\left(x^2+5\right)\left(x-3\right)\left(2x-1\right)< 0\)

\(\Leftrightarrow\left(x-3\right)\left(2x-1\right)< 0\) (vì \(x^2+5>0\forall x\))

\(\Rightarrow\dfrac{1}{2}< x< 3\)

17) \(x^2-6x+9>0\)

\(\Leftrightarrow\left(x-3\right)^2>0\)

\(\Rightarrow x-3\ne0\Leftrightarrow x\ne3\)

#$\mathtt{Toru}$