If f(x) = 3(x+5)+ 4/x what is f(a+2)

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  f(a+2) = (3a^2 +27a +46)/(a+2)  

Step-by-step explanation:

Put (a+2) where x is and simplify.

  f(a+2) = 3((a+2) +5) +4/(a+2)

  f(a+2) = 3(a +7) +4/(a+2)

  f(a+2) = 3a +21 +4/(a+2)

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We can combine the terms to a single rational expression.

  f(a+2) = ((3a +21)(a +2) +4)/(a+2) = (3a^2 +27a +42 +4)/(a+2)

  f(a+2) = (3a^2 +27a +46)/(a+2)