cho f(x)=0
\(\Rightarrow\)2x2-6x+2=0\(\Rightarrow\)2x2-3x-3x+2=0\(\Rightarrow\)(2x^2-3x)-(3x-2)=0\(\Rightarrow\)x(2x-3)-\(\frac{3}{2}\)(2x-3)+\(\frac{5}{2}\)=0\(\Rightarrow\)(2x-3)(x-\(\frac{3}{2}\))=0\(\Rightarrow\)2(x-\(\frac{3}{2}\))2=0 Từ đó suy ra dpcm rùi đó