FoG? If f(x)=2x^2+15 and g(x)=5 what is (F o G)(12) ?

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helpmepls!

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These questions are tricky for me but can someone show me a step by step on how they got the answer?

If f(x)=2x2+15 and g(x)=5 what is (F o G)(12) ?
 
ksdhart2 said:
What are your thoughts? What have you tried? For instance, you followed the typical process of function composition by first plugging the value of g(x) into f(x)... and then what? Please share with us all of the work you've done on this problem, even the parts you know sure are wrong. Thank you.
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I'm probably wrong but I plugged everything in and distributed it with the 12
 
helpmepls! said:
I'm probably wrong but I plugged everything in and distributed it with the 12
Click to expand...

Your use of the word "distributed" gives me the impression that you've fallen into the all too common trap of believing that the notation is telling you to multiply. The notation is not telling you to find (F o G) and then multiply by 12. (F o G) is a function, specifically f(g(x)). If we instead note this new function as h(x) = f(g(x)), then the full problem would be asking you to find h(12). You've seen that notation before and you know that it most definitely does not mean to multiply. Here, because g(x) is a constant function, h(x) is the same as f(5). What did you get when you evaluated this? What, then, does that mean about the value of h(12)? As a bonus exercise, to see if you really understand the concept, consider what would happen if you'd been given g(x) = 5x instead. Would that change the value of h(12)? Why or why not?
 
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