\[(5x - 2)(5x + 2) - (5x - 1)^{2} = 4\]
\[25x^{2} - 4 - 25x^{2} + 10x - 1 = 4\]
\[10x = 4 + 5\]
\[10x = 9\]
\[x = \frac{9}{10} = 0,9.\]