If f(x) = 4 – x2 and g(x) = 6x, which expression is equivalent to (g – f)(3)

For this case we have the following functions:
 
 The first thing we must do is subtract both functions.
 We have then:
 
 Substituting values we have:
 
 Rewriting we have:
 
 Then, we evaluate the function for x = 3.
 We have then:
 
 Rewriting:
 
 
 An expression that is equivalent to (g - f) (3) is:
 

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