a,= (435+565)-(360+140)= 1000-500= 500

b,= (121+879)+(581+419)= 1000+1000= 2000

a) 435-360+565-140

=(435+565)-(360-140)

=1000-220

=780

b)121+581+879+419

=(121+879)+(581+419)

=1000+1000

=2000

` (254 + 435) + 565 = 254 + ( 435+565)=254+1000=1254.`

`3,27 + 7,45 + 6,73= (3,27+6,73)+7,45= 10+7.45=17,45.`

`5/9 + ( 4/7 + 4/9 )= (5/9+4/9)+4/7=9/9+4/7= 1+4/7=11/7.`

a: =254+1000=1254

b: =3,27+6,73+7,45=10+7,45=17,45

c: =5/9+4/9+4/7=1+4/7=11/7

5,5 + \(\dfrac{3}{4}\) - 5 + \(\dfrac{1}{4}\)

(5,5 - 5) + (\(\dfrac{3}{4}\) + \(\dfrac{1}{4}\))

= 0,5  + 1

= 1,5 

\(\dfrac{5}{2}\) x  \(\dfrac{2}{3}\) + \(\dfrac{1}{4}\) : \(\dfrac{3}{2}\)

= \(\dfrac{5}{2}\) x \(\dfrac{2}{3}\) + \(\dfrac{1}{4}\) x \(\dfrac{2}{3}\)

=  (\(\dfrac{5}{2}\) + \(\dfrac{1}{4}\)) x \(\dfrac{2}{3}\)

= (\(\dfrac{10}{4}\) + \(\dfrac{1}{4}\)) x \(\dfrac{2}{3}\)

= \(\dfrac{11}{4}\) x \(\dfrac{2}{3}\)

= \(\dfrac{11}{6}\) 

Tính \(x\): 

  435  - [\(x\) + 16] = 425 : 17

  435 - [\(x\) + 16] = 25

          [\(x\) + 16] = 435 - 25

           \(x\) + 16 = 410

           \(x\)        = 410 - 16

          \(x\)         = 394

\(x\) x \(\dfrac{1}{4}\) - \(\dfrac{3}{4}\) = 6 : \(\dfrac{3}{4}\)

\(x\) \(\times\) \(\dfrac{1}{4}\) - \(\dfrac{3}{4}\) = 6 x \(\dfrac{4}{3}\)

\(x\) x \(\dfrac{1}{4}\) - \(\dfrac{3}{4}\)  = 8

\(x\) x \(\dfrac{1}{4}\)        = 8 + \(\dfrac{3}{4}\)

\(x\) x \(\dfrac{1}{4}\)        = \(\dfrac{32}{4}\) + \(\dfrac{3}{4}\)

\(x\) x \(\dfrac{1}{4}\)       = \(\dfrac{35}{4}\)

\(x\)              =  \(\dfrac{35}{4}\) : \(\dfrac{1}{4}\)

\(x\)              = \(\dfrac{35}{4}\) x 4

\(x\)             = 35

a) \(435-360+565-140\)

\(=\left(435+565\right)-\left(360+140\right)\)

\(=1000-500\)

\(=500\)

b) \(1+5+9+13+....+29\)

\(=\left(1+29\right)+\left(5+25\right)+\left(9+21\right)+\left(13+17\right)\)

\(=30+30+30+30\)

\(=30\times4\)

\(=120\)

a/ 435 - 360 + 565 - 140 

= ( 565 + 435 ) - ( 360 + 140 )

= 1000 - 500

= 500

b/ 1 + 5 + 9 + ... + 29

Tổng trên có số số hạng là:

( 29 - 1 ) : 4 + 1 = 8 ( số hạng )

Cứ nhóm 2 số hạng vào một nhóm ta được: 8 : 2 = 4 ( nhóm )

Ta có: 1 + 5 + 9 + ....... + 29 = ( 1 + 29 ) + ( 5 + 25 ) + .......

= 30 + 30 + ......

= 30 x 8

= 240

Nhớ k cho mình nhé! Thank you!!!

a, 435 - 360 + 565 - 140

= ( 435 + 565 ) - ( 360 + 140 )

= 1000            -   500

= 500

b, 1 + 5 + 9 + 13 + .... + 29

= ( 29 + 1 ) . 8 : 2

= 30 . 8 : 2 

= 240 : 2

= 120

\(a.145\times565+145\times54+56\times145\)

\(=145\times\left(565+54+56\right)\)

\(=145\times675\)

\(=97875\)

\(b.225\times104\)

\(=\left(100+4\right)\times225\)

\(=22500+900\)

\(=23400\)

\(c.1000:\left(20\times25\right)\)

\(=1000:500\)

\(=2\)

\(d.\left(206\times20\right):2\)

\(=206\times\left(20:2\right)\)

\(=206\times10=2060\)

 36-4x9 = 36 - 36 = 0 Vì số nào nhân với 0 thì cũng bằng 0 nên phép tính đó bằng 0

\(\frac{21}{11}\)x \(\frac{22}{17}\)x\(\frac{68}{63}\)

= \(\frac{42}{17}\)x\(\frac{68}{63}\)

= \(\frac{8}{3}\)

18 - x : 2 = 16

x : 2        = 18 - 16

x             = 2 x 2

x             = 4

\(\frac{21}{11}\times\frac{22}{17}\times\frac{68}{63}\)

\(=\frac{21}{11}\times\frac{22\times68}{17\times63}\)

\(=\frac{21}{11}\times\frac{22\times4}{1\times63}\)

\(=\frac{21}{11}\times\frac{88}{63}\)

\(=\frac{21\times88}{11\times63}\)

\(=\frac{1\times8}{1\times3}\)

\(=\frac{8}{3}\)

\(18-x:2=16\)

\(x:2=18-16\)

\(x:2=2\)

\(x=2\times2\)

\(x=4\)

Tính theo cách thuận tiện : 

21/11 × 22/17 × 68/63

= ( 21/11 × 68/63 ) × 22/17

= 68/33 × 22 / 17

= 8/3

Tìm x , biết : 

18-x:2=16

x:2=18-16

x:2=2

x=2×2

= 4

Vậy x = 4

Trả lời

Sửa đề câu a 1 tí

a)39/16:5/8-17/16:5/8+4/5

=(39/16-17/16):5/8+4/5

=11/8:5/8+4/5

=11/5+4/5

=15/5=3

b)16/17.12/19+16/17.7/19-2/3

=16/17.(12/19+7/19)-2/3

=16/17-2/3

=48/56-14/56

=34/56=17/28

Học tốt !

a) 2070 + 414 x 4 x 28 - 138 x 3 x 17 = 41400

b) 2020 x 14 + 4040 x 16 + 6060 x 18 = 72720

c) 42 x 477 + 14 x 336 x 3 + 84 x 92 - 42 = 41832

a) 2070 + 414 x 4 x 28 - 138 x 3 x 17 = 41400

b) 2020 x 14 + 4040 x 16 + 6060 x 18 = 72720

c) 42 x 477 + 14 x 336 x 3 + 84 x 92 - 42 = 41832