a. 5.(–8).( –2).(–3)
=(-2.5).(-8.-3)
=-10.24=-240
b. 4.(–5)2 + 2.(–5) – 20
=-5.(8+2+4)
=-5.14=-70
c. 27.(15 –12) – 15.(27 –12)
=27.15-27.12-15.27+12.15
=12.(15-27)
=12.-12=-144
d. 1 - 2 + 3 - 4 + 5 - 6+ ... + 199 - 200 ( có 200 số hạng )
=-1.100=-100