Question

Cho các đa thức sau hãy tính nghiệm:

1. 6x+3

2. -5x-7

3. (3x-2).(5-x)

4. x²-3x

5. (2x.1)²+(x+1)²

6. x⁴+8

Answer 1

1) \(6x+3=0\Leftrightarrow6x=-3\Leftrightarrow x=-\dfrac{1}{2}\)

2) \(-5x-7=0\Leftrightarrow-5x=7\Leftrightarrow x=-\dfrac{7}{5}\)

3) \(\left(3x-2\right)\left(5-x\right)=0\)

\(\Leftrightarrow\left[{}\begin{matrix}3x-2=0\\5-x=0\end{matrix}\right.\)\(\Leftrightarrow\left[{}\begin{matrix}x=\dfrac{2}{3}\\x=5\end{matrix}\right.\)

4) \(x^2-3x=0\Leftrightarrow x\left(x-3\right)=0\)

\(\Leftrightarrow\left[{}\begin{matrix}x=0\\x=3\end{matrix}\right.\)

6) \(x^4+8=0\)( vô lý do \(x^4+8\ge8>0\))

Vậy \(S=\varnothing\)