Bonjour,
b^3 + 5b^3 = 6b^3
-6y(y-5) = -6y^2 - 6y*(-5) = -6y^2 + 30y
-a - 8b + 3a + 5b = 2a - 3b
(3a - 2)(3a + 2) = (3a)^2 - 2^2 = 9a^2 - 4
d - (d - 2) = d - d + 2 = 2
(y - 4)^2 = y^2 - 2*y*4 + 4^2 = y^2 - 8y + 16
3m * 4m^2 = 3*4*m*m^2 = 12m^3
3(8 + t) + 6t = 3*8 + 3t + 6t = 9t + 24