\[x_{1} = - 0,4;\ \ \ \ \]
\[2x^{2} - 1,4x + c = 0\]
\[\left\{ \begin{matrix} x_{1} + x_{2} = \frac{1,4}{2} \\ x_{1} \cdot x_{2} = \frac{c}{2}\text{\ \ \ \ \ \ } \\ \end{matrix} \right.\ \]
\[- 0,4 + x_{2} = 0,7\ \ \]
\[x_{2} = 0,7 + 0,4\ \ \]
\[x_{2} = 1,1.\]
\[- 0,4 \cdot 1,1 = \frac{c}{2}\]
\[- 0,44 = \frac{c}{2}\text{\ \ }\]
\[c = - 0,88.\]
\[Ответ:\ c = - 0,88;\ \ x_{2} = 1,1.\]