Precalculus (6th Edition) Blitzer

Step 1. Graph the function $y=log(x)$ as shown with the red curve in the figure. Step 2. Graph the function $y=log(10x)$ as shown with the blue curve in the figure. It can be seen that this curve can be obtained by shifting the red curve up 1 unit. This is because $y=log(10x)=log(x)+log(10)=log(x)+1$ Step 3. Graph the function $y=log(0.1x)$ as shown with the green curve in the figure. It can be seen that this curve can be obtained by shifting the red curve down 1 unit. This is because $y=log(0.1x)=log(x)+log(0.1)=log(x)-1$