Đáp án:
1/2020+{743-[2020-(+257)]}
=2020+(743-2020+257)
=2020+743-2020+257=1000
2/175-(-25)+62-(1200+62)
=175+25+62-1200-62
=172+25-1200+(62-62)=-1000
3/3.(-5)²+2.(-5)-20
=3.25-10-20
=3.25-30=3.25-3.10=3.(25-10)=3.15=45
4/(-2).3.[44+(-3).4]:2³
=-6.32:2³=-6.4=-24
Chúc bn học tốt ^^