Répondre :
A(t)= (3t+1) au carré - (4t-1) au carré
=9t²+6t+1-16t²+8t-1
=-7t²+14t
B(t)= 9(t+1) au carré -4(2t + 3) au carré
=9(t²+2t+1)-4(4t²+12t+9)
=9t²+18t+9-16t²-48t-36
=-7t²-30t-27
C(t)= t au carré + 2t + 1 +(t+1) (3t-5)
=t²+2t+1+3t²-5t+3t-5
=4t²-4
D(t)= (2t + 1) au carré + 4t au carré - 1
=4t²+4t+1+4t²-1
=8t²+4t
=9t²+6t+1-16t²+8t-1
=-7t²+14t
B(t)= 9(t+1) au carré -4(2t + 3) au carré
=9(t²+2t+1)-4(4t²+12t+9)
=9t²+18t+9-16t²-48t-36
=-7t²-30t-27
C(t)= t au carré + 2t + 1 +(t+1) (3t-5)
=t²+2t+1+3t²-5t+3t-5
=4t²-4
D(t)= (2t + 1) au carré + 4t au carré - 1
=4t²+4t+1+4t²-1
=8t²+4t