I'm assuming all of (x^2+9) is in the denominator. If that assumption is correct, then,
One possible answer is 
Another possible answer is 
There are many ways to do this. The idea is that when we have f( g(x) ), we basically replace every x in f(x) with g(x)
So in the first example above, we would have

In that third step, g(x) was replaced with x^2+9 since g(x) = x^2+9.
Similar steps will happen with the second example as well (when g(x) = x^2)
(f-g) (x) means to subtract g(x) from f(x)
F(x) = 2x^2 +3
g(x) = x^2
This becomes:
2x^2 + 3 - x^2 = x^2 +3
Subtract 6 from both sides
15x= 195
Divide both sides by 15
x=13
Final answer: x=13
Check:
15(13)+6
195+6
201
201=201
9514 1404 393
Answer:
Step-by-step explanation:
The graph shows the function value is zero for x=5 and x=7. These are the elements of the solution set.
x ∈ {5, 7}
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The graph is below the x-axis between these points, so that is the region where f(x) < 0
5 < x < 7 . . . . . for f(x) < 0
In interval notation: (5, 7).