Réponse :
1) 4(x-2)
= 4x-4*2
=4x-8
2) b(5b+3)
=b*5b+3b
=5b^2+3b
3) 3x(4-9x)
=3x*4-3x*9x
=12x-27x^2
4) 2g(3g^2+5)
= 2g*3g^2+2g*5
= 6g^3+10g
5) 5(y+13)-4
= 5y+5*13-4
= 5y+61
6) 4(x-5)-10x
= 4x-4*5-10x
= 4x-20-10x
= -6x-20
7) -4(x+4)-8(7-2x)
= -4x-4*4-8*7-8*(-2x)
= -4x-16-56+16x
= 12x-72
8) 14c-7c(4-c)-2(3c-8)
= 14c-7c*4-7c*(-c)-2(3c-8)
= 14c-28c+7c^2-2(3c-8)
= 14c-28c+7c^2-2*3c-2*(-8)
= 14c-28c+7c^2-6c+16
= -20c + 7c^2+16