The point-slope form of a linear equation is [math]y - y_1 = m(x - x_1)[/math]. Move slider [math]m[/math]. The slope is [math]m[/math]. See the steepness of the line change. When [math]m[/math] is negative, the direction of the line changes. When [math]m = 0[/math], the line is flat. Move slider [math]x_1[/math] and [math]y_1[/math]. These make the point [math](x_1, y_1)[/math]. When there is only one point, the slope and the point can be used to find the equation of a line.