a) cho f(x) = 0
\(=>x^2-4=0=>x^2=4=>\left[{}\begin{matrix}x=2\\x=-2\end{matrix}\right.\)
b) cho g(x) = 0
\(=>\left(x+3\right)\left(2x-1\right)=0=>\left[{}\begin{matrix}x+3=0\\2x=1\end{matrix}\right.=>\left[{}\begin{matrix}x=-3\\x=\dfrac{1}{2}\end{matrix}\right.\)
a) \(f\left(x\right)=x^2-4=\left(x-2\right)\left(x+2\right)\)
Ngiệm là: \(\left[{}\begin{matrix}x=2\\x=-2\end{matrix}\right.\)
b) \(g\left(x\right)=\left(x+3\right)\left(2x-1\right)\)
Nghiệm là: \(\left[{}\begin{matrix}x=-3\\x=\dfrac{1}{2}\end{matrix}\right.\)
\(\text{a)Đặt f(x)=0}\)
\(\Rightarrow x^2-4=0\)
\(\Rightarrow x^2\) \(=0+4=4\)
\(\Rightarrow x\) \(=\pm2\)
\(\text{Vậy đa thức f(x) có 2 nghiệm là x=2;x=-2}\)
\(\text{b)Đặt g(x)=0}\)
\(\Rightarrow\left(x+3\right)\left(2x-1\right)=0\)
\(\Rightarrow\left[{}\begin{matrix}x+3=0\Rightarrow x=0-3=-3\\2x-1=0\Rightarrow2x=0+1=1\Rightarrow x=1:2=\dfrac{1}{2}\end{matrix}\right.\)
\(\text{Vậy đa thức g(x) có 2 nghiệm là x=-3;x=}\dfrac{1}{2}\)
