△= \(7^2+4.4.1=65\)
\(\Rightarrow x_1=\frac{7+\sqrt{65}}{8},x_2=\frac{7-\sqrt{65}}{8}\)
M = \(x_1^2+x_2^2=\left(\frac{7+\sqrt{65}}{8}\right)^2+\left(\frac{7-\sqrt{65}}{8}\right)^2=\frac{114+14\sqrt{65}+114-14\sqrt{65}}{64}=\frac{228}{64}=\frac{57}{16}\)
\(\Delta=49-4.\left(-1\right).4=65>0\) => pt có 2 n0 pb
\(Vi-et\Rightarrow\left\{{}\begin{matrix}x_1+x_2=\frac{7}{4}\\x_1x_2=-\frac{1}{4}\end{matrix}\right.\)
\(\Rightarrow M=x_1^2+x_2^2=\left(x_1+x_2\right)^2-2x_1x_2=\left(\frac{7}{4}\right)^2-2.\left(-\frac{1}{4}\right)=\frac{57}{16}\)
