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a) \(A=\left(-10\right)+\left(-34\right)+\left(-26\right)\)
\(=\left(-10\right)+\left[\left(-34\right)+\left(-26\right)\right]\)
\(=\left(-10\right)+\left(-60\right)\)
\(=-70\)
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a/ 35 – 2.1111 + 3. 72
= 35 - 2.1 + 3.49
= 35 - 2 + 147
= 33 + 147
= 180
b/ 5.43 + 2.3 – 81. 2 + 7
= 5.64 + 6 - 162 + 7
= 320 + 6 - 162 + 7
= 326 - 162 + 7
= 164 + 7
= 171
c/ 25 + 2.{12 + 2.[3.(5-2)+1]+1}+1
= 32 + 2.{12 + 2.[3.3+1]+1}+1
= 32 + 2.{12 + 2.10+1}+1
= 32 + 2.{12 + 20 + 1}+1
= 32 + 2.{32+1}+1
= 32 + 2.33 + 1
= 32 + 66 + 1
= 98 + 1
= 99
d/ 17.131 + 69.17
= 17 . (131+69)
= 17 . 200
= 3400
e/ 50 – [30 - (6 - 2)2 ]
= 50 - [30 - 42]
= 50 - 14
= 36
f/ 199 +36 + 201 + 184 + 37
= (199+201)+(36+184)+37
= 400 + 220 + 37
= 657
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a) 6857 + 3444 : 28
=6857 + 123
=6980
b) 80 - [ 130 - ( 75 - 11 ) ]
=80 - [ 130 - 64 ]
=80 - 66
=14
c) 100 : { 2 x [ 52 - ( 35 - 8 ) ]}
=100 : { 2 x [ 52 - 27 ]}
=100 : { 2 x 25 }
=100 : 50
=2
d) 12 : { 390 : [ 500 - ( 125 + 35 + 7 x 30 ) ] }
=12 : { 390 : [ 500 - ( 125 + 35 + 210 ) ] }
=12 : { 390 : [ 500 - 370 ] }
=12 : { 390 : 130 }
=12 : 3
=4
a) 6857 + 3444 : 28
=6857 + 123
=6980
b) 80 - [ 130 - ( 75 - 11 ) ]
=80 - [ 130 - 64 ]
=80 - 66
=14
c) 100 : { 2 x [ 52 - ( 35 - 8 ) ]}
=100 : { 2 x [ 52 - 27 ]}
=100 : { 2 x 25 }
=100 : 50
=2
d) 12 : { 390 : [ 500 - ( 125 + 35 + 7 x 30 ) ] }
=12 : { 390 : [ 500 - ( 125 + 35 + 210 ) ] }
=12 : { 390 : [ 500 - 370 ] }
=12 : { 390 : 130 }
=12 : 3
=4
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Sửa đề: A=7/12-9/20+11/30-13/42+15/56
A=1/3+1/4-1/4-1/5+1/5+1/6-1/6-1/7+1/7+1/8
=1/3+1/8=11/24
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Tham khảo
\(A=\left(b+a\right)+\left(c-d\right)-\left(c+a\right)-\left(b-d\right)\)
\(A=b+a+c-d-c-a-b+d\)
\(A=\left(b-b\right)+\left(a-a\right)+\left(c-c\right)+\left(-d+d\right)\)
\(A=0\)
\(B=\left(a-d\right)-\left(d+a\right)-\left(c-d\right)+\left(c+b\right)\)
\(B=a-d-d-a-c+d+c+b\)
\(B=\left(a-a\right)+\left(d-d+d\right)+\left(-c+c\right)+b\)
\(B=d+b\)
a) Ta có: \(A=\left(b+a\right)+\left(c-d\right)-\left(c+a\right)-\left(b-d\right)\)
\(=a+b+c-d-c-a-b+d\)
=0
b) Ta có: \(B=\left(a-d\right)-\left(a+d\right)-\left(c-d\right)+\left(c+b\right)\)
\(=a-d-a-d-c+d+c+b\)
=b-d
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a: \(42\cdot102-43\cdot17-42\cdot34\)
\(=42\left(102-34\right)-43\cdot17\)
\(=168\cdot17-42\cdot17\)
\(=17\cdot126=2142\)
c: \(3\cdot42-22\cdot3=3\cdot20=60\)
a) = -35 - 125
= -160
b) = -115 + 75
= -40
c) = -57 + 257
= 200
d) = 70 - 30
= 40
Tính giá trị của biểu thức:
a) \(-35+\left(-125\right)=-160\)
b) \(\left(-115\right)+75=-40\)
c) \(-57+\left|-257\right|=-57+257=200\)
d) \(\left|-70\right|+\left(-30\right)=70+\left(-30\right)=40\)