Topics such as linear and nonlinear equations and inequalities, compound inequalities, linear and nonlinear absolute value equations and inequalities, rational equations and inequality are commonly found in college algebra and precalculus textbooks. What is common about these topics is the fact that their solutions and graphs lie in the real line one-dimensional. However, sketching these graphs using computer software and graphing utilities is not straightforward. In this note we show how to use MathCAD to address this problem. The approach is simple and can be used by teachers in teaching almost all topics whose graphs and solutions lie in the real line. The method encourages students to explore mathematical models in these topics.