How do you find the domain of f(x)=(-3x^2)/(x^2+4x-45)?

1 Answer
Alan P.
Aug 5, 2016

Domain: all Real values except (-9) and (+5)

Explanation:

f(x)=(-3x^2)/(x^2+4x-45)
color(white)("XXX")will be defined for all Real values of x
color(white)("XXX")except those values which cause the denominator to be equal to zero.

That is the Domain will be all RR
except when
color(white)("XXX")x^2+4x-45=0

Factoring:
color(white)("XXX")(x+9)(x-5)=0

So the Domain of f(x) is
color(white)("XXX")RR-{-9,+5}

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