Symbolic analysis has been for some years a topic of interest in electronics, because it represents a way to have a better understanding on circuit behavior. Through this time, different approaches have been developed to obtain expressions that allow representing the circuit behavior and then try to improve its performance. These approaches have been done for example, through graphs methods, flow charts or analytical methods, like MNA or pure nodal analysis, which is the chosen method to be used in this Thesis. Nodal analysis utilized in this Thesis could not be employed without an important element in circuit analysis; it is the nullor, which can be employed to model different devices. But it is also useful for reducing the rank of matrices of the system being analyzed, by using the properties this element have. In this Thesis, a method for obtaining symbolic expressions is explained, and it is shown how the nullor helps creating the nodal formulation which allows getting those expressions. There is an open research in symbolic analysis due to the length of symbolic expressions and the necessity to reduce them in order they could be easier to be understood, this way, some simplification methods have been developed and presented in this Thesis, to show their usefulness to obtain shorter expressions. Within these reduction methods, a method of reducing order is treated, it is known as asymptotic waveform evaluation, and allows the reduction of order in expressions, to have smaller expressions. Symbolic analysis is also useful for calculating expressions that represent parameters like noise in amplifiers; this topic is also reviewed in this Thesis.