• An expression written in the form of $\frac{p(x)}{Q(x)}$ but $Q(x) \ne 0$ and $P(x), Q(x)$ are polynomials is called a rational expression. $P(X)$ is called a numerator, while $Q(X)$ is called the denominator.
• The domain of arational expression$\frac{P(x)}{Q(X)}$ is the set $\mathbb{R}_{Q(x) \ne 0}$.
• A Rational expression $\frac{P(x)}{Q(x)}$ is in its lowest form when the common factor of $P|(x)$ and $Q(x)$ is 1.

When the factor describing denominator are linear (That is, of the form $ax+b, a\neq 0$).

Assume the partial fraction as $\frac{Constant}{Factor}$.

i. Different factors of the form $\frac{P(x)}{ax+b}$.

ii. Factors with multiplicity, $\frac{P(x)}{(ax+b)^n}, n \in N$