2x2-10x+10=0
<=> x2-5x+5=0 ( chia cả 2 vế cho 2)
<=> \(x^2-2\times\frac{5}{2}x+\frac{25}{4}=\frac{5}{4}\)
<=> \(\left(x-\frac{5}{2}\right)^2=\frac{5}{4}\)
=> \(\orbr{\begin{cases}x=\sqrt{\frac{5}{4}}+\frac{5}{2}\\x=-\sqrt{\frac{5}{4}}+\frac{5}{2}\end{cases}}\)