Bonjour,
Développer puis réduire chaque expression :
a. (y+5) (y-4)
= y² - 4y + 5y - 20
= y² + y - 20
b. (4-3x) (x+2)
= 4x + 8 - 3x² - 6x
= - 3x² - 6x + 4x + 8
= - 3x² - 2x + 8
c.(v-8) (4v+2)
= 4v² + 2v - 32v - 16
= 4v² - 30v - 16
d. (3x+7) (2x-5)
= 6x² - 15x + 14x - 35
= 6x² - x - 35
e. ( 1/2 x -1) (4x+2)
= 4/2x² + 2/2x - 4x - 2
= 2x² + x - 4x - 2
= 2x² - 3x - 2
f. (-1/4x + 1/2) (x-4)
= - 1/4x² + 4/4x + 1/2x - 4/2
= - 1/4x² + x + 0,5x - 2
= - 1/4x² + 1,5x - 2