Functions :)
Homework problem. f(x) = 2x + 3 and g(x) = 9x - (1/2). Solve for f(14).
I know how to solve it (the output of g(x) = the input of f(x)) but I forgot how to start... Is it by substituting 14 for x in g(x)? Can't remember.

Question

Functions :)
Homework problem. f(x) = 2x + 3 and g(x) = 9x - (1/2). Solve for f(14).
I know how to solve it (the output of g(x) = the input of f(x)) but I forgot how to start... Is it by substituting 14 for x in g(x)? Can't remember.

campbell_st · Answer

well the question seems to ask for f(14)

so substitute x = 14 into f(x) = 2x + 3

hope that makes sense

anonymous · Answer

So i'm thinking it's going to start like this?
$$f(g(x)) = f(g(14))$$
$$f(x()) = f(9(14) - (1/2))$$
And that's how you start it? i can solve from there.

campbell_st · Answer

or is the question 

1. g(f(14)) ?

or

2. f(g(14)).?

anonymous · Answer

Well my teacher wrote it by hand so he might have meant find g(14)?

anonymous · Answer

If he wanted me to find f(14) it wouldn't make sense to give me the g(x) equation so i think he meant to say find g(14).

campbell_st · Answer

that's correct... 

but then it could have been included as a distraction... 

my advice... 

find g(14) 

then substitute the value into f(x)

and also find f(14) and then substitute it into g(x)

that covers most options

anonymous · Answer

Good plan. But back to the original question -- I forgot how to start out, so is my first statement correct? (as in f(g(x)) = f(9(14) - (1/2))

campbell_st · Answer

that's correct...

anonymous · Answer

Ok then, so...
$$f(125.5)$$
$$f(g(x)) = 2(125.5) + 3$$
$$f(g(x)0 = 254$$

anonymous · Answer

There's an abstract zero in there o.O didn't mean to put that. Thanks camp!

campbell_st · Answer

that's great well done