How do you find the domain of $(x^2 – x – 6 )/(x^2 – 9x + 18 )$ ?

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Answer 1 · 2016-06-16T18:18:07

$x!=3 and x!=6$

You can find the domain by excluding that the denominator is null, that's

$x^2-9x+18!=0$

or

$x!=(9+-sqrt(9^2-4*18))/2$

$x!=(9+-sqrt(81-72))/2$

$x!=(9+-sqrt(9))/2$

$x!=(9+-3)/2$

$x!=3 and x!=6$

How do you find the domain of (x^2 – x – 6 )/(x^2 – 9x + 18 )(x^2 – x – 6 )/(x^2 – 9x + 18 )?