Resposta:

a) a² + ab - ax - bx = a(a + b) - x(a + b) = (a - x)(a + b)

b) bx² - 2by + 5x² - 10y = b(x² - 2y) + 5(x² - 2y) = (x² - 2y)(b + 5)

c) 2an + n - 2am - m = (2a - 1)n - 2m(a + 1)

d) ax - bx + cx + ay - by + cy = x(a - b + c) + y(a - b + c) = (a - b + c)(x + y)