`x^2-2\sqrt{10}x+15/2=0`
Ptr có: `\Delta'=(-\sqrt{10})^2-15/2=5/2 > 0`
`=>` Ptr có `2` nghiệm pb
`x_1=[-b'+\sqrt{\Delta'}]/a=\sqrt{10}+\sqrt{10}/2=[3\sqrt{10}]/2`
`x_2=[-b'-\sqrt{\Delta'}]/a=\sqrt{10}-\sqrt{10}/2=\sqrt{10}/2`
\(x^2-2\sqrt{10}x+\dfrac{15}{2}=0\)
\(\Delta=\left(-2\sqrt{10}\right)^2-4.1.\dfrac{15}{2}=10\)
\(\Rightarrow\left\{{}\begin{matrix}x_1=\dfrac{2\sqrt{10}+\sqrt{10}}{2.1}\\x_2=\dfrac{2\sqrt{10}-\sqrt{10}}{2.1}\end{matrix}\right.=>\left\{{}\begin{matrix}x_1=\dfrac{3\sqrt{10}}{2}\\x_2=\dfrac{\sqrt{10}}{2}\end{matrix}\right.\)
