What is the slope of a straight line and what is its geometric meaning?

Consider a line of the form ax + by + c = 0. It can be converted to a straight line equal to y = – a / b * x – c / b, where k = -a / b and l = – c / a. Then we get: y = k * x + l. In this expression, k is the direct slope. Slope k – the ratio of the second coordinate to the first coordinate of the direction vector to the straight line, that is, k = (y – y0) / (x – x0). It can also be found by the formula k = tg a in a geometric way. … The geometric meaning is that the straight slope shows that the straight line y = k * x + b forms an angle with the Ox axis.