Check These Answers Please?

f(x)= x^2+3 ; g(x)=3x-1

1. (f+g)
=x^2+3x+2

2. (f+g)(3)
= 20

3. (f-g)(x)
= x^2+3x-4

4.(fg)(x)
= 3x^3+1x^2-9x+3

5. (fg)(x)
=5

6. (f/g)(x)
=(x^2+3)/(3x-1)

Compostitions of functions :

7. (f o g)(x)
=3x^2+4

8. (f o g)(x)
=10

1. ok

2. ok
3. (f-g)(x) = x^2 - 3x + 4
4. (fg)(x) = 3x^3 - x^2 + 9x - 3
5. (fg)(x) is not a number. Also, I find no value for x where (fg)(x) = 5
6. ok
7. (fog)(x) = f(g(x))
= g^2 + 3
= (3x-1)^2 + 3
= 9x^2 - 6x + 4
8. same as 5.