(35+75)+(345-35-75)

=35+75-345-35-75

=(35-35)+345+975-75)

(2002-79+15)-(-79+15)

=2002-79+15+79-15

=2002+(79-79)+915-15)

=2002.

-(515-80+91)-(2003+80-91)

=-515+80-91-2003-80+91

(-515)-2003+(80-80)+(91-91)

=2518.

( 35 + 75 ) + ( 345 - 35 - 75 )
= 35 + 75 + 345  - 35 - 75
= ( 35 - 35 ) + ( 75 - 75 ) + 345
= 0 + 0 + 345 
= 345 
( 2002 - 79 + 15 ) - ( -79 + 15 )
= 2002 - 79 + 15 + 79 - 15
= 2002 + ( -79 + 79 ) + ( 15 - 15 )
= 2002 + 0 + 0 
= 2002
- ( 515 - 80 + 91 ) - ( 2003 + 80 - 91 )
= -515 + 80 - 91 - 2003 - 80 + 91
= -515 + ( 80 -80 ) + ( -91 + 91 ) - 2003
= -515 + 0 + 0 - 2003
= - 2518

( 35 + 75 ) + ( 345 - 75 - 35 )

= 35 + 75 + 345 - 75 - 35

= ( 35 + 75 ) - ( 75 + 35 ) + 345

= 110 - 110 + 345

= 0 + 345

= 345

a) (35 + 75) +  (345 - 35 - 75)

= 35 + 75 + 345 - 35 - 75

= (35 - 35) + (75 - 75) + 345

= 0 + 0 + 345

= 345

b) (2002 - 79 + 15) - [ (-79) +15]

= 2002 - 79 + 15 - 79 - 15

= 2002 - (79 - 79) + (15 - 15)

= 2002 - 0 + 0

= 2002

c) -(515 - 80 + 91) - (2003 + 80 - 91)

= -515 + 80 - 91 - 2003 - 80 + 91

= -515 + (80 - 80) + (91 - 91) - 2003

= -515 + 0 + 0 - 2003

= -515 - 2003

= -2518

A. (35 + 75) + (345 - 35 - 75)

= 35 + 75 + 345 - 35 - 75

= (35 - 35) + (75 - 75) + 345

= 0 + 0 + 345

= 345

B. (2002 - 79 + 15) - (-79 + 15)

= 2002 - 79 + 15 + 79 - 15

= 2002 + (-79 + 79) + (15 - 15)

= 2002 + 0 + 0

= 2002

C. - (515 - 80 + 91) - (2003 + 80 - 91)

= -515 + 80 - 91 - 2003 - 80 + 91

= -515 - 2003 + (80 - 80) + (-91 + 91)

= -2518 + 0 + 0

= -2518

#Học tốt!!!

~NTTH~

<Cho hỏi ai k sai mik vậy, nếu sai làm ơn giải thử, nếu có thể chỉ ra lỗi sai của mik, đừng k sai trong khi câu trả lời là đúng>

Bài 7:

a) = 35 + 75 + 345 - 35 - 75

    = 345

b) = 2002 - 75 + 15 + 79 - 15

    = 2006

c) = - 515 + 80 - 91 - 2003 - 80 + 91

    = -2518

Bài 8:

a) = (4573 + 4573) + (46 - 16) + (35 - 5)

    = 9146 + 30 + 30

    = 9206

b) = (32 + 38) + (34+36) - (12+18) - (14+16) - 10

    = 70 + 70 - 30 - 30 - 10

    = 70

BÀI 7

a) (37+75)+(345-35-75)

=345

b) (2002-75+15)-(-79+15)

=2002

c) -(515-80+91)-(2003+80-91)

=-2518

BÀI 8 

a)4573+46+4573+35-16-5

=(4573+4573)+(46-10)+(35-5)

=9146+30+30

=9206

b) có 2 cách

bạn có thể làm theo cáchVũ Như Mai hoặc theo cách của mình

=32+34+36+38-10-12-14-16-18

=(32-12)+(34-14)+(36-16)+(38-18)-10

=20+20+20+20-10

=80-10=70

₁₎ ( 2002 - 79 + 15 ) - ( -79 + 15 ) = 2002 

₂₎ - (515 - 80+ 91 ) - ( 2003 + 80 + 91 ) = -2700 

₃₎ 4573 + 46 - 4573 + 35 - 16 - 5 = 60

₄₎ 32 + 34 + 36 + 38 - 10 - 12 - 14 - 16 - 18 = 70 

\(a)-7105-\left(155-7105\right)\)

\(=-7105-155+7105\)

\(=-7260+7105\)

\(=-155\)

\(b)35+75+\left(345-35-75\right)\)

\(=35+75+345-35-75\)

\(=110+345-35-75\)

\(=455-35-75\)

\(=420-75\)

\(=345\)

\(c)\left(2002-79+15\right)-\left(-79+15\right)\)

\(=2002-79+15+79+15\)

\(=1923+15+79+15\)

\(=1938+79+15\)

\(=2017+15\)

\(=2032\)

\(d)-\left(515-80+891\right)-\left(2003+80-91\right)\)

\(=-515-80+891-2003-80+91\)

\(=-595+891-2003-80+91\)

\(=296-2003-80+91\)

\(=-1707-80+91\)

\(=-1787+91\)

\(=-1696\)

Bỏ dấu ngoặc rồi tính:

a)(2015-79+19)-(-79+19)

b)-(515-80+91)-(2020+80-91)

Giải:

a,Ta có:(2015-79+19)-(-79+19)=2015-79+19+79-19

=2015-79+79+19-19

=2015+0+0=2015

b,-(515-80+91)-(2020+80-91)=-515+80-91-2020-80+91

=-515-2020+80-80-91+91

=-2535+0+0=-2535

a) (2015-79+19)-(-79+19)

= 2015 - 79 +19 + 79 -19

= 2015 + (79- 79) + (19 -19)

= 2015

b) - (515 - 80 +91) -(2020 +80-91)

= -515 + 80 - 91 - 2020 -80 +91

= -515 -2020 +( 80 -80) + (91 -91)

= -2535

a) (35 + 75) + (345 - 35 - 75)

= 35 + 75 + 345 - 35 - 75 ( quy tắc mở ngoặc đổi dấu)

= (35 - 35) + ( 75 - 75) + 345

= 345

b) (2003 - 79 + 15) - (-79 + 15)

= 2003 - 79 + 15 + 79 - 15 (quy tắc mở ngoặc đổi dấu)

= 2003 + ( 79 - 79) + (15 - 15)

= 2003

c) -(515 - 80 + 91) - (2003 + 80 - 91)

= -515 + 80 - 91 - 2003 - 80 + 91 ( quy tắc mở ngoặc đổi dấu)

= (80 - 80) + (91 - 91) + ( -2003 - 515)

= -2518

d) 4575 + 46 - 4573 + 35 - 16 -5

= (4575 - 4573) + (46 - 16) + (35 - 5)

= 2 + 30 + 30

= 62

Chúc học tốt!!

a) ( 35 + 75 ) + ( 345 - 35 - 75 )

= 35 + 75 + 345 - 35 - 75

= ( 35 - 35 ) + ( 75- 75 ) + 345

= 0 + 0 + 345

= 345

Bài 1:

a) \(24 - (-15) - 2\)

\(=39-2\)

\(=37\)

b) \((-85) + 10 - (-85) - 50\)

\(=[(-85)-(-85)]+10-50\)

\(=0+10-50\)

\(=10-50\)

\(=-40\)

c) \(71 - (-30) - (+18) + (-30)\)

\(=[(-30)-(-30)]+71-(+18)\)

\(=0+71-18\)

\(=71-18\)

\(=53\)

d) \(-(30) - (+37) + (+37) + (-85)\)

\(=[-(+37)+(+37)]-(30)+(-85)\)

\(=0-(30)+(-85)\)

\(=(-30)+(-85)\)

\(=-115\)

e) \((35-815) - (795-65)\)

\(=(-780)-730\)

\(=-1510\)

g) \((2002-79+15) + (-79+15)\)

\(=1938+(-64)\)

\(=1874\)

Bài 2:

a) \(25 - (30+x) = x - (27-8)\)

\(25-30-x=x-27+8\)

\(x+x=25-30+27-8\)

\(2x=14\)

\(x=14\div2\)

\(x=7\)

b) \((x-12) - 15 = (20-17) - (18+x) \)

\(x-12-15=13-18-x\)

\(x-27=-5-x\)

\(x+x=-5+27\)

\(2x=22\)

\(x=22\div2\)

\(x=11\)

c) \(15 - x = 7 - (-2)\)

\(15-x=9\)

\(x=15-9\)

\(x=6\)

d) \(x - 35 = (-12) - 3\)

\(x-35=-15\)

\(x=-15+35\)

\(x=20\)

e) \(\left|5-x\right|-26=-15\)

\(\left|5-x\right|=-15+26\)

\(\left|5-x\right|=11\)

Từ đây ta có:

*Nếu \(5-x=11\)

\(x=5-11\)

\(x=-6\)

*Nếu \(5-x=-11\)

\(x=5-(-11)\)

\(x=16\)

Vậy \(x=-6;x=16\)