Bài 8: Quy tắc dấu ngoặc

j: =>2x+6=200-64=136

=>2x=130

=>x=65

k: =>5(x+4)=1100

=>x+4=220

=>x=216

l: =>9(x+4)=5*4+25=45

=>x+4=5

=>x=1

a:=>7x=21

=>x=3

b: =>10x=100

=>x=10

c: =>8x=3^3*4+12=27*4+12=120

=>x=15

d: =>6x=68-8=60

=>x=10

h: =>x-5=0

=>x=5

g: =>x^4=2^4

=>x=2 hoặc x=-2

d: \(=50+34+\dfrac{\left[20-8\right]}{2}=84+6=90\)

e: \(=50+\dfrac{\left[50-8\cdot5\right]}{2}+3=53+5=58\)

f: \(=129+5\left[29-25\right]=129+20=149\)

\(\dfrac{1}{3}x-0,75x+\dfrac{1}{6}x-\dfrac{27}{32}=0\\ x\left(\dfrac{1}{3}-\dfrac{3}{4}+\dfrac{1}{6}\right)=\dfrac{27}{32}\\ \left(\dfrac{4-9+2}{12}\right)x=\dfrac{27}{32}\\ -\dfrac{1}{4}x=\dfrac{27}{32}\\ x=\dfrac{-27}{8}\)

=>1/3x-1/4x+1/6x-27/32=0

=>1/4x=27/32

=>x=27/8

=>1/3x-1/4x+1/6x-27/32=0

=>1/4x=27/32

=>x=27/8

\(=28+30-4=44\)

28+30-4=44

\(=-37+7=-30\)

(-45+8)+[-5-(-12)]

= -45 + 8 - 5 + 12

= ( -45 - 5 ) + ( 8 + 12 )

= -50 + 20

= -30

\(=-35+7=-28\)

=2017-2789+1789-2017=-1000

`-(-2017+2789) +(1789-2017)`

`=2017 - 2789 + 1789 -2017`

`=(2017-2017) + (-2789 + 1789)`

`=0 + (-2789 + 1789)`

`=0 + (-1000)`

`=-1000`

\(=-772-228=-1000\)

`5 - ( 1997 - 2006 ) + 1997`

` =5 - 1997 - 2006 + 1997`

`= (-1997 + 1997) +2006 + 5`

`=0 + 2006 + 5`

`=2011`

____________________________

`4567 + ( 1234 - 4567 ) - 4`

`=4567 + 1234 - 4567 - 4

`=(4567-4567)+1234 - 4`

`=0 + 1234 - 4`

`=1230`

____________________________

`1579 - ( 53 + 1579 ) - (-53)`

`=1579 -53 - 1579 + 53`

`=(1579 - 1579) + (53 - 53)`

`=0 + 0`

`=0`

___________________________

`2001 - 15 + 54 - 2001 - 54`

`=(2001 -2001) + (54-54) - 15`

`=0 + 0 - 15`

`=0 - 15`

`=-15`

___________________________________

`#H.J`

a: =(21-22)+(23-24)=-1-1=-2

b: =125-115+99=10+99=109

c: \(=232-250-132=100-250=-150\)

d: \(=12-57+57+\left(-12\right)=0\)

a, 21 - 22 + 23 - 24

= ( 21 - 22 ) + ( 23 - 24 ) 

= -1 + (-1)

= -2

b, 125 - ( 115 - 99 )

= 125 - 115 + 99

= 10 + 99

= 109

c, 232 - ( 581 + 132 - 331 )

= 232 - 581 - 132 + 331

= ( 232 - 132 ) + ( 331 - 581 )

= 100 + ( - 250 )

= -150

d, [ 12 + (-57) ] - [ -57 - (-12) ]

= 12 - 57 + 57 + 12

= ( 12 + 12 ) + [ 57 + ( - 57 ) ]

= 24 + 0

= 24

\(a, 21 - 22 + 23 - 24\)

\(= ( 21 - 22 ) + ( 23 - 24 ) \)

\(= -1 + (-1) = -2\)

\(--------------\)

\(b, 125 - ( 115 - 99 )\)

\(= 125 - 115 + 99 \)

\(= (125 - 115) + 99 \)

\(= 10 + 99 = 109\)

\(--------------\)

\(c, 232 - ( 581 + 132 - 331 )\)

\(= 232 - 581 - 132 + 331 \)

\(= ( 232 - 132 ) - ( 581 - 331 )\)

\(= 100 - 250 = -150\)

\(--------------\)

\(d, [ 12 + (-57) ] - [ -57 - (-12) ]\)

\(= ( 12 − 57 ) − ( − 57 + 12 ) \)

\(= 12 − 57 + 57 − 12\)

\(= ( 12 − 12 ) + ( 57 − 57 )\)

\(= 0 + 0 = 0\)

\(\text{# Hàn Thiên Vy}\)

1, (-5) + (-18) - (+9) + (+3)

= -5 - 18 - 9 +3=-29

2, (-5) - (-8) + (+15) + (-10)

= -5 + 8 + 15 - 10 =8

3, -(+7) - (-12) + (-9) + (-10)

= -7 + 12 - 9 - 10 =-14

4, 16- (-3) + (-5) - (+7) + 12

= 16 + 3 - 5 - 7 +12 =19