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(f◦g)(x)
f(x) = 3x
f(g) = 3g
but, g = 3x^2-2x+3
so, f(g) = 3(3x)^2 - 2(3x) + 3 = 9x^2 - 6x + 3
similarly, for (g◦f)(x)
g(f) = 3f^2 - 2f + 3
= 3(3x)^2 - 2(3x) + 3 = 27x^2 - 6x + 3