svp aidez-moi !!! Cst l'exercice 18

bonjour

G(x) = 9 x² - 12 x + 4 - 3 ( 4 x² - 3 x+ 8 x - 6)
G(x) = 9 x² - 12 x + 4 - 12 x² + 9 x - 24 x + 18
G(x) = - 3 x² - 27 x + 22

H(x) =  2 x² /3 + x/9 - 6 x/2 - 3/6
H( x) =  12 x²/18 + 2 x /18 - 54 x/18 - 9/18
H(x) = 12 x² - 52 x - 9 

I(x) = x² - 25 + 3 ( x² + 2 x + 1)
I(x) = x² - 25 + 3 x² + 6 x + 3
I(x) = 4 x² + 6 x - 22