Question

(1 + 2i) * (5 - 3i) * (- 4 - 1)

Answer 1

(1+2i)*(5-3i)=5-3i+10-6i=-9i+15--->>>> (-9i+15)*(-4-1)=(-9i+15)*(-5)= 45-75i

Answer 2

$(1 + 2i) * (5 - 3i) * (- 4 - 1)= \\ Propiedad Distributiva: \\ \\ (1(5-3i) + 2i (5-3i)) *(-4-1)= \\ \\ Aplicamos la Propiedad Distributiva: \\ \\ (1*5+1 (-3i) + 2i (5-3i))) *(-4-1)= \\ Volvemos a aplicar la Propiedad Distributiva: \\ \\ (1*5+1 (-3i) + (2i*5+2i (-3i)))*(-1-4)= \\ Quitamos el par\'entesis: \\ \\ (1*5+1 (-3i) +2i*5+2i (-3i))*(-1-4)= \\ \\ (5-3i+10i+6)*(-5)= \\ \\ (11+7i)*(-5)= \\ Aplicamos la propiedad distributiva: \\ \\ 11*(-5)+7i*(-5)= \\ \\ \boxed{ -55+35i}$

Saludos!!