Tolong bantuin soal no. 6-8 Mohon bantuannya

6.(gof)(x) = g(f(2))
=g(2(2)^2 + 5(2) - 7)
=g (2(4)+10-7)
=g(8+10-7)
=g(11)
=3(11) - 12
= 33 - 12
=21. B

7.(gof) (x) =g(f(x))
=g(x-3)
=(x-3)^2 + 2(x-3)
=x^2 -3x-3x+9 +2x-6
=x^2-4x+3 . C

8.(fog)(x) =f(g(x))
=f(2x-1)
=3(2x-1)^2 + 10(2x-1) - 8
=3(4x^2 - 2x - 2x +1 ) + 20x - 10 - 8
= 3(4x^2 - 4x + 1) + 20x - 10 - 8
= 12x^2 - 12x + 3 + 20x - 10 - 8
= 12x^2 + 8x - 15

Maaf kalau salah :)
koreksi lagi ya..