## anonymous 4 years ago f(x) = -2x-1 and h(x) = 3/x+1 what does (h*f)(2) = ??

1. Hero

f(x) = -2x-1 h(x) = 3/(x+1) f(2) = -2(2) - 1 = -4 - 1 = -5 h(2) = 3/(2+1) = 3/3 = 1 (h*f)(2) = h(2)*f(2) = 1*-5 = -5

2. Mertsj

f(2)=-5 h(2)=1 f(2)*h(2)=-5(1)=-5

3. anonymous

Is that a valid way of writing f(2)*h(2) ?

4. Hero

* means times. It's valid for when you're using a computer or a calculator

5. anonymous

I meant (h*f) seems like multiplying "functions" rather than their values. Do you understand what I mean?

6. Hero

Yes, you can also multiply the functions, but that would take longer. It's easier to evaluate f(2) and h(2) then multiply that together. Either way, you would get the same answer.

7. anonymous

Thank you

8. anonymous

hmmmm......i got the answer -3/4 ?? that is the answer in the book i am using.

9. anonymous

depends on whether you want $f\times g(x)$ or $f\circ g(x)$ they are different

10. anonymous

ok that makes sense b/c the question was (h o f)(2)

11. anonymous

then $h\circ f(2)=h(f(2))=h(-5)=\frac{3}{-5+1}=-\frac{3}{4}$