bài 2:
c) \(x^3+8x^2+17x+10=0\)
\(\Leftrightarrow\)\(x^3+x^2+7x^2+7x+10x+10=0\)
\(\Leftrightarrow\)\(x^2\left(x+1\right)+7x\left(x+1\right)+10\left(x+1\right)=0\)
\(\Leftrightarrow\)\(\left(x+1\right)\left(x^2+7x+10\right)=0\)
đến đây thì dễ rồi, bn cm x^2 + 7x + 10 > 0