a) 285 + 470 + 115 + 230

= (285 + 115) + (470 + 230)

= 400 + 700

= 1 100

b) 571 +216 + 129 + 124

= (571 + 129) + (216 + 124)

= 700 + 340

= 1 040.

a) 2763 + 152 = 2915

\(2915\)

1x\(10^{17}\)

100000000000000000

cho mik cách giải

\(a.\) \(50\cdot374\cdot2=\left(50\cdot2\right)\cdot347=100\cdot347=34700\)

\(b.\)\(36\cdot97+97\cdot64=97\cdot\left(36+64\right)=97\cdot100=9700\)

\(c.157\cdot289-289\cdot57=289\cdot\left(157-57\right)=289\cdot100=28900\)

\(a)\left(-17\right)+\left(-23\right)+44=-40+44=4\)

\(b)\left(-39\right)+\left(-16\right)+39=\left[\left(-39\right)+39\right]+\left(-16\right)=0+\left(-16\right)=-16\)

a) (- 17) + (- 23) + 44;

= (- 40) + 44

= 4

b) (- 39) + (- 16) + 39.

= (- 39) + 39 + (- 16)

= 0 + (- 16)

= - 16

a) (- 17) + (- 23) + 44

=  [ (- 17) + (- 23) ] + 44 

=  (- 40) + 44

= 4

b) (- 39) + (- 16) + 39

= [ (- 39) + 39 ] + (- 16)

= 0 + (- 16)

= -16

41.29 + 41.70 + 41

= 41.(29 + 70 + 1)

= 41. { (29+1) + 70}

= 41.(30 + 70)

= 41.100

= 4100

= 37.(72 - 5 + 33)

=37.{ (72 + 33) - 5}

= 37. (105 - 5)

= 37. 100

= 3700 

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.

a) 29,42 + 20,58 - 34,23 + (-25,77)

=(29,42+20,58)+(-34,23+-25,77)

=50+-60

=-10

b) (-212,49) - (87,51 - 99,9) 

=-212,49-87,51+99,9

=(-212,49-87,51)+99,9

=-300+99,9

=-200,1

`a) 29,42 + 20,58 - 34,23 + (-25,77)`
`=29+0,42+20+0,58-34-0,23-25-0,77`
`=29+20-34-25+0,42+0,58-(0,23+0,77)`
`=49-59+1-1`
`=-10`
`b) (-212,49) - (87,51 - 99,9).`
`=-212,49-87,51+99,9`
`=-(212,49+87,51)+99,99=`
`=-299,9+99,9`
`=-200`

a) 29,42+20,58-34,23+(-25,77)

=🥰💓👍🦹🤝💓🥰👍🤝🦹👍🥰💓🤝🦹👍🥰💓

Lời giải:

$A=(1-4)+(7-10)+(13-16)+....+(97-100)+103$

$=\underbrace{(-3)+(-3)+(-3)+...+(-3)}_{17}+103$

$=(-3).17+103=52$