Combining functions - just another check

[Agent_J]

combining functions - just another check :)

f(x) = 2/x
g(x) = x/x+2

fog = f(g(x))
= f(x/x+2)
=2/x/x+2
=2 * x+2/x
=2x+2/x

[Edit (by ahrkron): no changes; took back my edit (I meant to reply)... the post is now in its original form]

 

[outandbeyond2004]

Better recheck the last two equations.
2*(x+2)/x is what you meant, is it not?

 

[ahrkron]

Be careful. Use parentheses, and you most probably need to think about the domain of both functions (what values of x are excluded on each case? what about the composition?).

 

[Agent_J]

oh ya, I forgot to distribute the 2

how would I find the domain ahrkron

 

[cookiemonster]

For what values of x are f(x) and g(x) undefined? Those will be out of the domain.

cookiemonster

 

[matt grime]

The domain should be given otherwise it isnt' a function. At some point teachers and basic textbook writers are going to learn this.