F(x)=3x+7 G(x)=x²-2x+5 (FoG)(x)

fog(x) = f(g(x))
= f (x^2 - 2x +5)
= 3 (x^2 - 2x +5) +7
= 3x^2 - 6x +15 +7
=3x^2 - 6x +22

(f ° g )(x) = 3(x²-2x+5) + 7
= (3x ² - 6x + 15) + 7

yang didalam kurung dibagi 3 setiap koefisiennya
= x² - 2x + 5 + 7
= x² - 2x + 12