Posted by **Alicia** on Friday, June 12, 2009 at 10:16am.

Given that f(x) = x^2-3 and g(x) = 2x+1, find each of the following, if it exists.

a. (fg)(-root3)

b. (gf)(-1/2)

- Algebra -
**Reiny**, Friday, June 12, 2009 at 11:19am
do you mean f(g(x)) ?

f(g(x))

= (g(x))^2 - 3

= (2x+1)^2 - 3

then (f(g(-√3))

= (-2√3 + 1)^2 - 3

= 12 - 4√3 + 1 - 3

= 10 - 4√3

do the other one the same way

remember this time you want

g(f(x))

= g(x^2-3)

= 2(x^2-3) + 1

- Algebra -
**Alicia**, Friday, June 12, 2009 at 11:26am
The first one was (fg)(-root3). Does this answer your ? Thanks for the help!

- Algebra -
**Alicia**, Friday, June 12, 2009 at 11:34am
What happend to the (-1/2) in the second problem?

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