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A; 2015+37-2016-47
= (2016-2015)+(47-37)
= 1 + 1 =2
B;34+35+36+37-14-15-16-17
= (34-14)+(35-15)+(36-16)+(37-17)
= 20 + 20 + 20 + 20 = 80
C ;-7624 + (1543+7624) bổ ngoặc rồi tính
= -7624 +1543+7624
= (7624+-7624)+1543
= 0 +1543 = 1543
D; (27-514) -(486-73) quy tắc đổi dấu
= 27-514 -486-73
= -27 + -514 + -486 + -73
= (-27+-73)+(-486+-514)
= -100 + -1000 = -1100
=
106.
\(9-25=\left(7-x\right)-\left(25+7\right)\)
\(-16=\left(7-x\right)-32\)
\(\left(7-x\right)-32=-16\)
\(7-x=-16+32\)
\(7-x=16\)
\(-x=16-7\)
\(-x=9\)
\(x=-9\)
\(\text{Vậy }x=-9\)
107. a) 2575 + 37 – 2576 – 29 = ( 2575 – 2576 ) + ( 37 – 29 ) = -1 + 8 = 7
b) 34 + 35 + 36 + 37 – 14 – 15 – 16 – 17
= ( 34 – 14 ) + ( 35 – 15 ) + ( 36 – 16 ) + ( 37 – 17 )
= 20 + 20 + 20 + 20 = 80
108.
a) – 7624 + ( 1543 + 7624 )
= -7624 + 1543 + 7624
= (-7624 + 7624)+1543
= 0 + 1543
= 1543
b) ( 27 – 514 ) – ( 486 – 73 )
= 27 - 514 - 486 + 73
= (27 + 73) - (514 + 486)
= 100 - 1000
= -900
108: Tính nhanh:
a)-7624+(1543+7624)
=-7624+1543+7624
=(-7624+7624)+1543
=0+1543=1543
b)(27-514)-(486-73)
=27-514-486+73
=(27+73)-(514+486)
=100-1000=-900
\(\text{( -12 ) + ( -13 ) + 36 + ( - 11 )}\)
\(=\left[\left(-12\right)+\left(-13\right)+\left(-11\right)\right]+36\)
\(=\left(-36\right)+36\)
\(=0\)
\(\text{- 16 + 24 + 16 _ 34}\)
\(=\left(-16+16\right)+\left(24-34\right)\)
\(=0+\left(-10\right)\)
\(=-10\)
\(\text{25 + 37 _ 48 _ 25_ 37}\)
\(=\left(25-25\right)+\left(37-37\right)-48\)
\(=0+0-48\)
\(=-48\)
\(\text{2575 + 37 _ 2576 _ 29}\)
\(=\left(2575-2576\right)+\left(37-29\right)\)
\(=\left(-1\right)+8\)
\(=7\)
\(\text{34 + 35 + 36 + 37 _ 14 _ 15 _ 16 _ 17}\)
\(=\left(34-14\right)+\left(35-15\right)+\left(36-16\right)+\left(37-17\right)\)
\(=10+10+10+10\)
\(=40\)
\(\text{( 27 + 514 ) _ ( 486 _ 73 )}\)
\(=27+514-486+73\)
\(=\left(27+73\right)+\left(514-486\right)\)
\(=100+28\)
\(=128\)
chúc bạn học tốt
Bài 1: tính hợp lí:
( -12 ) + ( -13 ) + 36 + ( - 11 )
= [ - 12 + ( - 13 ) + ( - 11 ) ] + 36
= ( - 36 ) + 36
= 0
- 16 + 24 + 16 - 34
= ( - 16 + 16 ) + ( 24 - 34 )
= 0 + ( - 10 )
= - 10
25 + 37 - 48 - 25 - 37
= ( 25 - 25 ) + ( 37 - 37 ) - 48
= 0 + 0 - 48
= - 48
2575 + 37 - 2576 - 29
= ( 2575 - 2576 ) + ( 37 - 29 )
= - 1 + 8
= 7
34 + 35 + 36 + 37 - 14 - 15 - 16 - 17
= ( 34 - 14 ) + ( 35 - 15 ) + ( 36 - 16 ) + ( 37 - 17 )
= 20 + 20 + 20 + 20
= 20 x 4
= 80
Bài 2: bỏ dấu ngoặc rồi tính:
( 27 + 514 ) - ( 486 - 73 )
= 27 + 514 - 486 + 73
= ( 27 + 73 ) + ( 514 - 486 )
= 100 + 28
= 128
a) (-37)+14+26+37 = ( -37 + 37) + ( 14 + 26) = 40
b) (-24)+6+10+24 = ( - 24 + 24) + ( 6 + 10) = 16
c) 15+23+9-25)+(-33) = (15 - 25) + ( 23 - 33) + 9
= - 10 - 10 + 9
= - 11
d) 60+33+(-50)+(-33) = ( 60 -50) + ( 33 - 33)
= 10
e) (-16)+(-209)+(-14)+209 = ( - 16 - 14) + ( - 209 + 209)
= - 30
g) (-12)+(-13)+36+(-11)= ( - 11 -12 - 13 ) + 36
= - 36 + 36 = 0
h) -16+24+16-34 = ( - 16 + 16)+(24 - 34) = - 10
r) 25+37-48-25-37 = (25 - 25)+(37 - 37) - 48 = - 48
u) 2575+37-2576-29 = ( 2575 - 2576) + ( 37 - 29)
= - 1 + 8 = 7
i) 34+35+36+37-14-15-16-17 = ( 34 - 14 )+(35 - 15)+(36-16)+ (37 - 17)
= 80
2 . Bỏ ngoặc rồi tính
a)-7264+(1543+7264) = - 7264 + 1543 + 7264
= 1543
b) (144-97)-144 = 144 - 97 - 144 = - 97
c) (-145)-(18-145) = - 145 - 18 + 145 = - 18
d) 11+(-11+27) = 11 - 11 + 27 = 27
e) (27+514)-(486-73) = 27 + 514 - 486 + 73
= 128
g) (36+79)+(145-79-66) = 36 + 79 + 145 - 79 - 66
= 115
h) 10-[12-(-9-1) = 10 - ( 12 + 9 + 1)
= 10 - 22
= - 12
r) (-28-29+43)-(43+38) = - 28 - 29 + 43 - 43 - 38
= - 95
u ) 271 - [(-43)+271-(-17)] = 271 + 43 - 271 - 17 = 26
i ) -144-[29-(+144)-(+144) = - 144 - 29 - 144 + 144 = -173
-7624 + ( 1543 + 7624 )
= -7624 + 1543 + 7624
= ( -7624 + 7624 ) + 1543
= 0 + 1543
= 1543
( 27 - 514 ) - ( 486 - 73 )
= 27 - 514 - 486 + 73
= ( 27 + 73 ) - ( 514 + 486 )
= 100 - 1000
= -900
-7624 + ( 1543 + 7624 )
= ( -7624 + 7624 ) + 1543
= 0 + 1543
= 1543
( 27 - 514 ) - ( 486 - 73 )
= ( -487 ) - 413
= -900
a)-7624+(1543+7624)=(-7624+7624)+1543=1543
b)(27-514)-(486-73)=27-514-486+73=(27+73)-(514-486)=100-28=72
a)2575 + 37 + 2576 -29
= ( 2575 - 2576 ) + ( 37 - 29)
= -1+ 8
= 8-1
= 7
a, \(2575+37-2576-29\)
\(=\left(2575-2576\right)+\left(37-29\right)\)
\(=\left(-1\right)+8=7\)
P/s: Cấm k :>