Expressed as a graph this function is a straight line which intersects the vertical axis (represented by f(x)) when x=0, at -6, and the horizontal x axis when f(x)=0, i.e., at x=2. Join these two points together and the result is part of the graph. We have a right-angled triangle with the right angle at point (0,0), the origin of the graph, and the hypotenuse is the line joining (0,-6) and (2,0). The slope of the hypotenuse is the difference quotient or differential. It's the ratio of the vertical side of the remaining two sides to the horizontal and evaluates to 6/2=3. 6 is the f(x) or vertical displacement between the points and 2 is the horizontal displacement. The result 3 is the multiplier in the expression for f(x). The difference quotient (called quotient because of the division that's used to calculate it) is always the multiplier for every straight line graph, and this multiplier can be negative as well as positive. Negative multipliers change the slope from positive (like a forward slash /) to negative (like a back slash \).