$\text{Câu 7:}$
`A(1) = 1^3 - 5.1.m + m^2 = 1 - 5m + m^2`
`B(-2) = 3m^2 + 3m . (-2) + 1 = 3m^2 - 6m + 1`
`A(1) = B(-2)`
`⇒ 1 - 5m + m^2 = 3m^2 - 6m + 1`
`⇔ -5m + 6m + m^2 - 3m^2 = 1 - 1`
`⇔ m - 2m^2 = 0`
`⇔ m(1 - 2m) = 0`
\(⇔\left[ \begin{array}{l}m=0\\1-2m=0\end{array} \right.\)
\(⇔\left[ \begin{array}{l}m=0\\2m=1\end{array} \right.\)
\(⇔\left[ \begin{array}{l}m=0\\m=\dfrac{1}{2}\end{array} \right.\)
$\text{Vậy}$ `x ∈ {0; 1/2}`
