giup
Bài 1 :
a)17 . 85 + 15 . 17 -120=17.(85+15)-120=17.100-120=1700-120=1580
b)75-(3.5^2-4.3^2)=75-(3.25-4.9)=75-(75-36)=75-39=36
c)A=12:{390:[500-(125+35.7)]}
=>A=12:{390:[500-(125+245)]}
=>A=12:{390:[500-370]}
=>A=12:{390:130}
=>A=12:3
=>A=4
d)B=10+12+....+96+98
=>B=(98+10).45
(vi tu 10 den 98 co (98-10):2+1=45)
=>B=108.45
=>B=4860
Bài 2:
a)2.5^2+3:71^0-54:3^3
=2.25+3:1-54:27
=50+3-2
=51
b)189+73+211+127
=(189+211)+(73+127)
=400+200
=600
c)375:{32-[4+(5.3^2-42)]}-14
=375:{32-[4+(5.9-42)]}-14
=375:{32-[4+(45-42)]}-14
=375:{32-[4+3]}-14
=375:{32-7}-14
=375:25-14
=15-14
=1
Bài 3:
a)38.73+27.38
=38.(73+27)
=38.100
=3800
b)5.3^2-32:4^2
=5.9-32:16
=45-2
=43
c)5.2^3+7^11:7^9-1^8
=5.8+7^2-1
=40+49-1
=88
d)400:{5.[360-(290+2.5^2)]}
=400:{5.[360-(290+2.25)]}
=400:{5.[360-(290+50)]}
=400:{5.[360-340]}
=400:{5.20}
=400:100
=4
e)2^3.2^4.2^6
=2^3+4+6
=2^13
(=8192)
f)9^6:3^2
=9^6:9
=9^5
(=59049)
giup