Reciprocal of Linear and Quadratic Functions
The reciprocal of a function \(f(x)\) is given by \(g(x) = \frac{1}{f(x)}\).
Reciprocal of a Linear Function
Consider a linear function \(f(x) = mx + b\). The reciprocal is \(g(x) = \frac{1}{(mx + b)}\).
Graphing:
- If \(f(x) = 0\), then g(x) is undefined, resulting in a vertical asymptote.
- If \(f(x)\) is positive, then g(x) is also positive.
- If \(f(x)\) is negative, then g(x) is also negative.
Example
Let’s graph the reciprocal of the function \(f(x) = 2x + 1\).
- Identify the zeros of \(f(x): x = \frac{-1}{2}\) (vertical asymptote).
- Determine the sign of \(f(x)\): negative for \(x < \frac{-1}{2}\), positive for \(x > \frac{-1}{2}\).
- Sketch the graph of g(x) using this information.