How do you evaluate #-5x^3+7x^2# for #x=-1# and for #x=3#?

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Answer 1 · 2017-06-24T13:09:49

#f(-1)=12# and #f(3)=-72#

When #f(x)=-5x^3+7x^2#, there will be two values of #f(x)#, one when #x=-1# and two when #x=3#.

As such #f(-1)=-5(-1)^3+7(-1)^2#

= #-5xx(-1)+7xx1#

= #5+7#

= #12#

and #f(3)=-5(3)^3+7(3)^2#

= #-5xx27+7xx9#

= #-135+63#

= #-72#