what does the equation y = mx + c mean? It means a straight line with slope 3 and y-intercept (0,c) For instance y = 2x - 3 is a straight line with slope 2 and y-intercept (0,-3), and has this graph:For instance y = -4x + 1 is a straight line with slope -4 and y-intercept (0,1), and has this graph: Edwin AnlytcPhil@aol.com