Répondre :
((1/3)-(3/4)a)^2=(1/3)^2-2*(1/3)*(3/4)a+(3/4)^2*a^2=(1/9)-(1/2)a+(9/16)a^2
((1/2)x-4)^2=(1/2)^2x^2-2*(1/2)*4x+16=(1/4)x^2-4x+16
((1/2)x-4)^2=(1/2)^2x^2-2*(1/2)*4x+16=(1/4)x^2-4x+16