developper et reduire A=(7t+3)(4-2 t)-6(-t+2) ensuite avec t=o et t=-3/7
A = 28t-14t²+12-6t-(-6t+12)
A = 28t -14t²+12-6t+6t-12
A = -14t²+28t-6
Pour t = 0, A = 0
Pour t =3/7
A = -14*(3/7)² + 28*3/7 -6
= -14*9/49 + 84/7-6
= -126/49 + 84/7 - 6
= -126/49 + 588/49 - 294/49
= 168/49
= 24/7
A = 28t-14t²+12-6t-(-6t+12)
A = 28t -14t²+12-6t+6t-12
A = -14t²+28t-6
Pour t = 0, A = 0
Pour t =3/7
A = -14*(3/7)² + 28*3/7 -6
= -14*9/49 + 84/7-6
= -126/49 + 84/7 - 6
= -126/49 + 588/49 - 294/49
= 168/49
= 24/7
c comme l'a di nullasse
