$\text { Đáp án: }$
$\text { c) }$
$\text { H(x) + Q(x) = –2x³ – 3x² + 1 }$
$\text { ⇒ H(x) = (–2x³ – 3x² + 1) – Q(x) }$
$\text { ⇒ H(x) = (–2x³ – 3x² + 1) – (–2x³ + x² – 9x + 1) }$
$\text { ⇒ H(x) = –2x³ – 3x² + 1 + 2x³ – x² + 9x – 1 }$
$\text { ⇒ H(x) = –2x³ + 2x³ – 3x² – x² + 9x + 1 – 1 }$
$\text { ⇒ H(x) = –4x² + 9x }$
$\text { Vậy H(x) = –4x² + 9x. }$
