a) \(x^3-9x^2+6x+16\)
\(\Leftrightarrow x^3+x^2-10x^2+10x-4x-4+20\)
\(\Leftrightarrow x^2\left(x+1\right)-10x\left(x+1\right)-4\left(x+1\right)+20\)
\(\Leftrightarrow\left(x+1\right)\left(x^2-10x-4+20\right)\)
\(\Leftrightarrow\left(x+1\right)\left(x^2-10x+16\right)\)
Vì (x+1) chia hết cho x+1 => \(\left(x+1\right)\left(x^2-10x+16\right)\) chia hết cho x+1
Câu b) Tương tự
Chúc học tốt !!