4x /(x^2-2x-15) factor the denominator as (x - 5)(x +3)
And since anything that makes the denominator 0, is undefined......then this rational function will be undefined when x = 5 or x = -3
See the graph, here: https://www.desmos.com/calculator/81t61hpgz7
Hello Guest!
Find all numbers for which the
rational expression is not defined.
4x / (x2 - 2x - 15)
The rational expression is undefined
when the denominator is zero.
x² - 2x - 15 = 0
\(x = {2 \pm \sqrt{4+60} \over 2}\)
\(x= \frac{2\pm 8}{2} \)
\(x_{1}= 5\ \ x_{2}= - 3 \)
The rational expression is undefined when
\(x\in \left\{5, -3 \right\} \)
Greeting asinus :- ) !