(5х-1)•(2х+1)-10х=0,8

To solve the given equation, first we need to expand the left side: (5x - 1)(2x + 1) - 10x = 0.8 Expanding the left side gives us: 10x^2 + 5x - 2x - 1 - 10x = 0.8 Simplifying further: 10x^2 + 3x - 1 - 10x = 0.8 10x^2 - 7x - 1 = 0.8 Now, we have a quadratic equation in the form of ax^2 + bx + c = 0. We can solve it using the quadratic formula: x = (-b ± √(b^2 - 4ac)) / 2a In this case, a = 10, b = -7, and c = -1. Plugging these values into the formula, we get: x = (7 ± √((-7)^2 - 4*10*(-1))) / 2*10 x = (7 ± √(49 + 40)) / 20 x = (7 ± √89) / 20 Therefore, the solutions to the equation are: x = (7 + √89) / 20 and x = (7 - √89) / 20.