Question

Làm giúp em câu 17 18 19:((

Answer 1

\(c17;f\left(x\right)=x^2-\left(m+2\right)x+4m+1\)

\(\Leftrightarrow\Delta>0\Leftrightarrow\left(m+2\right)^2-4\left(4m+1\right)=m^2-12m>0\Leftrightarrow\left[{}\begin{matrix}m< 0\\m>12\end{matrix}\right.\)

\(c18:\)\(x^2-2\left(m+1\right)x+m^2+3< 0\)

\(\Leftrightarrow\Delta'\le0\Leftrightarrow\left(m+1\right)^2-m^2-3\le0\Leftrightarrow m\le1\)

\(c19:\Leftrightarrow\Delta'\ge0\Leftrightarrow m^2-1\ge0\Leftrightarrow m^2\ge1\Leftrightarrow\left|m\right|\ge1\)

 

Answer 2

Câu 17: A

Câu 18: B

Câu 19: A