Please help with this question on functions?

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2 Answers
Apr 30, 2018

See below

Explanation:

The way I interpret the question is that you have the function
#f(x)#, each with its own restricted domain.

Domain= the values #x# is allowed to take in the function.

The question really states, when translated into words that:

Given the function #f(x),# where if #x# is greater than 4, the function of #f# is equal to 3x-5. If instead #x# is less than or equal to 4 then a function of #x# is equal to #x^2#.

Thus;

  1. If #x# is greater than 4, apply #f(x)=3x-5#
    2.If #x# is less than or equal to 4, apply #f(x)=x^2#

Hence in 1.:

#f(7)=3(7)-5=21-5=16#

For 2.:
#f(4)=4^2=16#

As the equation states that #f(x)=x^2# applies if #x# is less than OR equal to #4#.

For 3.: #4>x# as #x=-3# so we must apply the first function.

#f(-3)=(-3)^2=9#

Apr 30, 2018
  1. 16
  2. 16
  3. 9

Explanation:

#f(7) =># substitute #x=7 # into #3x-5=21-5=16 #
because #x>4#

#f(4) =># substitute #x=4# into #x^2=4^2=16#
because #x=4#

#f(-3) =># substitute #x=-3# into #x^2=(-3)^2=9#
because #x<4#