\[(2x - 5)^{2} - 2 \cdot (7x - 1)^{2} =\]
\[= 4x^{2} - 2 \cdot 10x + 25 - 2 \cdot \left( 49x^{2} - 2 \cdot 7x + 1 \right) =\]
\[= 4x^{2} - 20x + 25 - 98x^{2} + 28x - 2 =\]
\[= - 94x^{2} + 8x + 23\text{.\ }\]