bonsoir,
a= (2+x) (15-y)
= 2X15 - 2Xy + xX15 - xXy
= 30 - 2y + 15x - xXy
b= (7+y) (y-4)
=7Xy - 7X4 + yXy - yX4
= 7y - 28 + y² - 4y
= 3y -28 +y²
c= (z-25) (x+2)
= zXx + zX2 - 25Xx - 25X2
= zXx +2z -25x - 50
d= (t-3) (t-13)
= tXt - tX13 - 3Xt + 3X13
= t² - 13t - 3t + 39
= t² - 16t + 39
bonne soirée
