Question

Giải phương trình :

ɑ, \(x^2-3x+3=0\)

b, \(x-\left(x-2\right)-\left(x-2\right)=0\)

c, \(\left(x\text{-2}\right)\left(x\text{-}1\right)=0\)

d, \(x^2-2x-x+2=0\)

Answer 1

a ) \(x^2-3x+3=0\)

\(\Leftrightarrow x^2-3x+\dfrac{9}{4}+\dfrac{3}{4}=0\)

\(\Leftrightarrow\left(x-\dfrac{3}{2}\right)^2=-\dfrac{3}{4}\) ( Vô lý , \(\left(x-\dfrac{3}{2}\right)^2\ge0\forall x\) )

\(\Rightarrow\) Pt vô nghiệm

b ) \(x-\left(x-2\right)-\left(x-2\right)=0\)

\(\Leftrightarrow x-2\left(x-2\right)=0\)

\(\Leftrightarrow x-2x+4=0\)

\(\Leftrightarrow4-x=0\)

\(\Leftrightarrow x=4\)

Vậy ...

c ) \(\left(x-2\right)\left(x-1\right)=0\)

\(\Leftrightarrow\left[{}\begin{matrix}x-2=0\\x-1=0\end{matrix}\right.\Leftrightarrow\left[{}\begin{matrix}x=2\\x=1\end{matrix}\right.\)

Vậy ...

d ) \(x^2-2x-x+2=0\)

\(\Leftrightarrow x\left(x-2\right)-\left(x-2\right)=0\)

\(\Leftrightarrow\left(x-1\right)\left(x-2\right)=0\)

\(\Leftrightarrow\left[{}\begin{matrix}x-1=0\\x-2=0\end{matrix}\right.\Leftrightarrow\left[{}\begin{matrix}x=1\\x=2\end{matrix}\right.\)

Vậy ...