How do I write the equation of a rational function given these characteristics
Olivia Zamora
- $Y$ intercept at $-5$
- No $x$ intercepts
- Discontinuous points at $(-1,-5)$ and $(3, -5)$
This was on an assignment, please help! Edit: the graph is NOT linear
$\endgroup$ 33 Answers
$\begingroup$Hint: Discontinuous points come from common factors in the numerator and denominator, so you should be able to find two factors of the denominator from item 3. Since you have no $x$ intercepts, the function should not go through zero, and it sounds like you don't want vertical asymptotes. It looks like a nice graph that satisfies your needs would be the line $y=-5$ less the two discontinuous points.
$\endgroup$ 2 $\begingroup$$$y=\left(\frac{x+1}{\left| x+1\right|}\right)\left(\frac{x-3}{\left|x-3\right|}\right)-4$$
$\endgroup$ $\begingroup$$$y=\sin(2\pi x)-7+\left(\frac{x+1}{x+1}\right)+\left(\frac{x-3}{x-3}\right)$$
Explanation: $\sin$ term to make it non-linear and no x intercept
$-7$ to account for y intercept
Fractional terms to account for discontinuities (You can only simplify those to $1$ if $x\neq-1$ or $3$)
$\endgroup$