3 (2x-4)² - 5 (2x + 3)( 1 - 7) aider moi svp il faut développer

f(x)=3(2x-4)²-5(2x+3)(x-7)
   =3(4x²-16x+16)-5(2x²-11x-21)
   =2x²+7x+153

3 (2x-4)² - 5 (2x + 3)(1 - 7)== 3((2x)²-2*2x*4+4²)-5(2x*1-2x*7+3-3*7)= 3(4x²-16x+16)-5(2x-14x+3-21)= 3(4x²-16x+16)-5(12x-18)= (3*4x²-3*16x+3*16)-(5*12x -5*18)= (12x²-48x+48)-(60x - 90)= 12x²-48x +48-60x + 90= 12x²-48x -60x + 90+48= 12x²-(48+60)x + 138= 12x²-108x + 138