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#