View Full Version : Solving function compositions
Katherine2007
Aug 1, 2007, 08:23 AM
If f(x)= x^4 +7 and g(x) = x+5 and h(x) =x^1/2
then what does
f o g o h (x) =??
Capuchin
Aug 1, 2007, 08:46 AM
what is the o meant to represent?
you mean f(g(h(x))) ?
Katherine2007
Aug 1, 2007, 09:08 AM
what is the o meant to represent?
you mean f(g(h(x))) ?
Yes.
Capuchin
Aug 1, 2007, 09:19 AM
okay so that means you need to put h(x) as x into g(x), and then put that result (g(h(x))) as x into f(x).
for example if m(x) = 1+x and n(x) = x+2 then m(n(x)) is putting n(x) as x into m(x) so it's 1+(n(x)) = 1+(x+2) = 3+x
now can you do yours?
Katherine2007
Aug 1, 2007, 09:27 AM
okay so that means you need to put h(x) as x into g(x), and then put that result (g(h(x))) as x into f(x).
for example if m(x) = 1+x and n(x) = x+2 then m(n(x)) is putting n(x) as x into m(x) so it's 1+(n(x)) = 1+(x+2) = 3+x
now can you do yours?
so then
x^1/2 + 5 then becomes the (x) that you plug into f(x)= x^4 +7
?
just to double check x^1/2 is the same as the sqrt of x right?
Capuchin
Aug 1, 2007, 09:30 AM
Yup and yup.
Katherine2007
Aug 1, 2007, 09:37 AM
so then
x^1/2 + 5 then becomes the (x) that you plug into f(x)= x^4 +7
??
just to double check x^1/2 is the same as the sqrt of x right?
thanks, I got the right answer now! The computer was throwing me off a bit because it wouldn't recognize x^1/2... I had to enter it as x^.5... but your example really helped! I've never had calculus or pre-calculus and the last math I had was 5 years ago!