Salut !
4a + 4b = 4(a+b)
2x + 8 = 2x + 2×4 = 2(x+4)
3x² - 3x = 3x×x + 3x×1 = 3x(x+1)
2(x-1) + x(x-1) = (x-1)(2+x)
3x(5-6x) = 15²-18x²
x+8(x+8) = x+8x+64 = 9x+64
3(x-2)+2x(6+x) = 3x-6+12x+2x² = 2x²+15x-6
-8(-3x+7)-(-2-x²) = 24x-56+2+x² = x²+24x-54
(x+5)(7+3x) = 7x+3x²+35+15x = 3x²+22x+35