Bài 1:tính hợp lý ( nếu có thể )
A.
a) 1125-(374+1125)+(-65+374)
b) -23×63+23×21-58×23
c)-2003+(-21+75+2003)
d) 942-2567+2563-1942
e) 13-12+11+10-9+8-7+5-4+3+2-1
g) 210+[46+(-210)+(-26)]
h) (-8)-[(-5)+8]
i) 25×134+25×(-34)
B.
a)17-25+55-17
b) 25-(-75)+32-(32+75)
c) (-5)×8×(-2)×3
d) (-15)+(-122)
e) |-127|-18×(5-6)
g) 100+(+430)+2145+(-530)
h) (-12)×15
i) (+12)×13+13×(-22)
k) {[14:(-2)]+7}:2012
Bài 1:tính hợp lý ( nếu có thể ) A. a) 1125-(374+1125)+(-65+374) b) -23×63+23×21-58×23 c)-2003+(-21+75+2003) d) 942-2567+2563-1942 e) 13-12+11+10-9+8-
By Maya
Bài 1: A
a) 1125-(374+1125)+(-65+374)
=1125-374-1125-65+374
=(1125-1125)+(-374+374)-65
=0+0-65
=-65
b) -23×63+23×21-58×23
=-23×(63-21+58)
=-23×100
=-2300
c)-2003+(-21+75+2003)
=-2003-21+75+2003
=(-2003+2003)+(-21+75)
=0+54
=54
d) 942-2567+2563-1942
=(942-1942)+(-2567+2563)
=-1000-4
=-1004
e) 13-12+11+10-9+8-7+5-4+3+2-1
= (13-12)+(11+10-9+8)+(-7+5-4+3+2-1)
=1+20-2
=19
g) 210+[46+(-210)+(-26)]
=210+46-210-26
=(210-210)+(46-26)
=0+20
=20
h) (-8)-[(-5)+8]
=-8+5-8
=(-8-8)+5
=-16+5
=-11
i) 25×134+25×(-34)
=25×(134-34)
=25×100
=2500
B
a)17-25+55-17
=(17-17)+(-25+55)
=0+30
=30
b) 25-(-75)+32-(32+75)
=25+75+32-32-75
=25+(75-75)+(32-32)
=25+0+0
=25
c) (-5)×8×(-2)×3
=(-5)×(-2)×8×3
=10×8×3
=240
d) (-15)+(-122)
=-15-122
=-137
e) |-127|-18×(5-6)
=127-18×(-1)
=127+18
=145
g) 100+(+430)+2145+(-530)
=100+430+2145-530
=100+2145+(430-530)
=100+2145-100
=2145
h) (-12)×15
=-180
i) (+12)×13+13×(-22)
=13×(12-22)
=13×(-10)
=-130
k) {[14:(-2)]+7}÷2012
={-7+7}÷2012
=0÷2012
=0
A.
a,1125-(374+1125)+(-65+374)
=1125-1499+309
=(-374)+309
=-65
b,-23×63+23×21-58×23
=-1449+483-1334
=-2300
c,-2003+(-21+75+2003)
=-2003+-21+75+2003
=[(-2003)+2003]+[(-21)+75]
=0+54
=54
d,942-2567+2563-1942
=-1625+621
-1004
e,13-12+11+10-9+8-7+5-4+3+2-1
=1+21-17-12-7+1
=22-5-8
=17-8
=9
g,210+[46+(-210)+(-26)]
=210+[-164+-26]
=210+-190
=20
h,(-8)-[(-5)+8]
=(-8)-(-5)+8
=[(-8)+8]-(-5)
=0+5
=5
i,25×134+25x(-34)
=25×134+(-34)
=25×100
=2500