17 :
11(x+3) = 11*x+11*3 = 11x + 33
4(3-t) = 4*3-4*t = 12-4t
9(a+b) = 9*a+9*b = 9a+9b
2(7+3b) = 2*7+2*3b = 14+6b
(a-4+2y)*3 = 3*a-3*4+3*2y = 3a-12+6y
19 :
30 + 5x = 5*5+5*x = 5(5+x)
7m + 28 = 7*m+7*4 = 7(m+4)
12x2 + 20x = 4x*3x+4x*5 = 4x(3x+5)
Voilà je suis pas sur
