bài 3 : tính nhanh

a) (42*43+43*57+43)-360:4

ngoặc vuông43.(42+57+1) ngoặc vuông -90

43.100-90

4300-90

4210

b.

a) (42*43 + 43*57 + 43) - 360:4

= 43*(42+57+1) - 90

= 43*100 - 90

= 4300 - 90

= 3410

a)2500

b)2772

c)1974

d)347

e)1874

k mk nha

a,25x100=2500

b,

1, 3 và 6

2, câu này thì nhiều

3, a,6   b,26

4 mấy câu còn lại thì cậu ấn máy tính

b)1482:x+23=80

1482:x=80-23

1482:x=57

x=1482:57

x=26

\(27.332+93.43+57.61+69.57\\ =27.332+93.43+57.\left(61+69\right)\\ =27.332+93.43+57.130\\ =8964+3999+7410=20373\\ 34.75+75.66-65.100\\ =\left(34+66\right).75-65.100\\ =100.75-65.100\\ =100.\left(75-65\right)\\ =100.10=1000\\ \left(456.11+912\right).37:13:74\\ =5928:13:\left(74:37\right)\\ =456:2=228\\ 6^2:4.3+2.5^2\\ =36:4.3+2.25\\ =9.3+50=27+50=77\\ 5.4^2-18:3^2\\ =5.16-18:9\\ =80-2=78\\\left[\left(315+372\right).3+\left(372+315\right).7\right]:\left(26.13+74.14\right)\\ =687.\left(3+7\right):\left(338+1036\right)\\ 687.10:1374\\ =6870:1374=5\\ 12:\left\{390:\left[500-\left(125+35.7\right)\right]\right\}\\ =12:\left[390:\left(500-370\right)\right]\\ =12:\left(390:130\right)=12:3=4\\ 192000-\left(1500.2+1800.3+1800.2:3\right)\\ =192000-\left(3000+5400+1200\right)\\ =192000-9600=182400\)

Bài 1:
a) 248 + (-12) + 2064 + (-236)
= 248 - 236 + 2064 - 12
=       12     +     2052
=             2064
b) (-298) + (-300) + (-302)
= -298 - 302 - 300
=      -600 - 300
=          -900
c) 5 + (-7) + 9 + (-11) + 13 + (-15)
=     -2      -      2       -        2
=                      -6
d) (-6) + 8 + (-10) + 12 + (-14) + 16
=       2     +        2      +        2
=                       6
e) 456 + [58 + (-456) + (-38)]
= 456 - 456 + 58 - 38
=        0      +    20
=               20

Bài 2:
a) 8 - (3 + 7)
= 8 - 3 - 7
=     -2
b) (-5) - (9 - 12)
= -5 - 9 + 12
=       -2
c) (5674 - 97) + (97 + 18 - 5674)
= 5674 - 97 + 97 + 18 - 5674
=                  18
d) (13 - 135 + 49) - (13 + 49)
= 13 - 13 - 135 + 49 - 49
=            -135
e) x + 8 - (x + 22)
= x + 8 - x - 22
=        -14
f) - (x + 5) + (x + 10) - 5
= -x - 5 + x + 10 - 5
=             0

lấy máy tính ra bạn ơi tick mình nhaaaaaaaaa

các bạn tính hẳn câu C hộ mình dc ko

Bài 6:

\(21,251+6,058+0,749+1,042\)

\(=\left(21,251+0,749\right)+\left(6,058+1,042\right)\)

\(=22+7,1\)

\(=29,1\)

___________________

\(1,53+5,309+12,47+5,691\)

\(=\left(1,53+12,47\right)+\left(5,309+5,691\right)\)

\(=14+11\)

\(=25\)

5:

a: =>x/17=5/17

=>x=5

b; =>6+x=7/11*33=21

=>x=15

c: \(\dfrac{12+x}{43-x}=\dfrac{2}{3}\)

=>3x+36=86-2x

=>5x=50

=>x=10

d: \(\dfrac{x}{5}< \dfrac{3}{7}\)

=>x<3/7*5

=>x<15/7

f: 15/26+x/16=46/52

=>x/16=23/26-15/26=8/26=4/13

=>x=4/13*16=64/13

`@` `\text {Ans}`

`\downarrow`

`456 \div2\times18 + 456\div3 - 102`

`= 456\times0,5\times18 + 456\times1/3 - 102`

`= 456\times (0,5 \times 18 + 1/3) - 102`

`= 456 \times(9 + 1/3) - 102`

`= 456 \times28/3 - 102`

`= 4256 - 102`

`= 4154`

=456*9+456:3-102

=4104+152-102

=4104+40

=4144