Bonsoir,
Utiliser la double distributivité :
(a + b)(c + d) = ac + ad + bc + bd
C = (3z + 4)(5 - 6z)
C = 3z*5 + 3z*(-6z) + 4*5 + 4*(-6z)
C = 15z - 18z² + 20 - 24z
C = -18z² + 15z - 24z + 20
C = -18z² - 9z + 20
✅
D = (-7t + 8)(3 - 5t)
D = -7t*3 + (-7t)*(-5t) + 8*3 + 8*(-5t)
D = -21t + 35t² + 24 - 40t
D = 35t² - 21t - 40t + 24
D = 35t² - 61t + 24
✅
* = multiplication
Bonne soirée.
