(2-i).(-3+2i).(5-4i)=

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

=(2. -3) + (2.2i) + (-1 . -3) + (-1 . 2i) .(5-4i)

= (-6 + 4i + 4 -2i) . (5-4i)

= (5 . -6) + (5 . 4i) + (5.4) + (5.-2i) + (-4i . -6) + (-4i .4i) + (-4i.4) + (-4i . -2i)

= -30 + 20i + 20 -10i + 24i -16i^2 -16i +8i^2

=-30+20+20i-10i+24i-16i-16i^2+8i^2

=-10 +18i-8i^2