What is the domain and range of #y=x^2-9#?

1 Answer
Alan P.
Apr 25, 2018

Assuming we are limited to Real numbers:
Domain: #x inRR#
Range: #yin[-9,+oo)#

Explanation:

#y=x^2-9# is defined for all Real values of #x# (actually it is defined for all Complex values of #x# but let's not worry about that).

If we are restricted to Real values, then #x^2>=0#
which implies #x^2-9 >= -9#
giving #y=x^2-9# a minimum value of #(-9)# (and no limit on its maximum value.) That is it has a range from #(-9)# up to positive inifinite.

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