1. ## (fog)(x) and (gof)(x)

Consider the functins f(x) = the square root of x + 3

and

g(x) = x^2 - 3.

a) (fog) (x)

b) (gof) (x)

c) (f+g) (x)

d) (fg) (x)

I know the rules for combing the functions:

Can somebody help check behind me on c) and d) and show me a) and b)?

Thanks again. K

2. ## Re: (fog)(x) and (gof)(x)

$f(x) = \sqrt{x+3}\\ g(x) = x^2-3$

a) (fog) (x)
$f(g(x)) = \sqrt{g(x)+ 3} = \sqrt{x^2-3+3} = |x|$

b) (gof) (x)
$g(f(x)) = (\sqrt{x+3})^2 - 3 = ...$

c) (f+g) (x)
$f(x) + g(x) = ...$

d) (fg) (x)
$f(x) \times g(x) = ...$

3. For:

a) (fog) (x) = 400.07 ?

b) (gof) (x) = 400 ?

c) (f = g) (x) = 400.500 ? ?

d) (fg) (x) = 693.107 ? ? ?

Correct?

K

4. Originally Posted by kjones
For:

a) (fog) (x) = 400.07 ?

b) (gof) (x) = 400 ?

c) (f = g) (x) = 400.500 ? ?

d) (fg) (x) = 693.107 ? ? ?

Correct?

K
How can we check if you haven't given us an x value?

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