tính bằng cách thuận tiện nhất :

12,56 + 3,42 x 5,6 x ( m + 1 - m - 1 )

=

tính bằng cách thuận tiện nhất :

12,56 + 3,42 x 5,6 x ( m + 1 - m - 1 )

=12,56+3,42x5,6x (1+1-m-m)

=(12,56+3,42)x5,6x(2-0)

=(1598+2)x5,6

=1600x5,6

=8960

T i c k

cảm ơn

a)53,49\(\times\)0,704+46,51\(\times\)0,704

=(53,49+46,51)\(\times\)0,704

=100x0,704

=70,4

b)8,30×617,32+8,30×382,68

=8,30x(6,17+382,68)

=8,30x 388,85

= 3227.455

c)3,42×2,5×0,4.

= 3,42x(2,5x0,4)

=3,42x1

=3,42

d)8,25×0,125×8×2.

= (8,25x2)x(0,125x8)

=16,5x1

=16,5

nhanh

3,42 : 0,57 x 8,4 - 6,8

= 6 x 8,4 - 6 - 0,8

= 6 ( 8,4 - 1 ) - 0,8

= 6 x 7,4 - 0,8

= 43,6

Muốn nhanh thì đây:

       Đ/s:43,6

a)

`127+246+273+354`

`=(127+273)+(246+354)`

`=400+600`

`=1000`

b)

`1,58+3,04+6,96+3,42`

`=(1,58+3,42)+(3,04+6,96)`

`=5+10`

`=15`

c)

`1/2+1/3+1/5+1/6`

`=(1/2+1/3+1/6)+1/5`

`=(3/6+2/6+1/6)+1/5`

`=6/6+1/5`

`=1+1/5`

`=5/5+1/5`

`=6/5`

a, 127 + 246 + 273 + 354

= ( 127 + 273) + ( 246 + 354)

= 400 + 600

= 1000

b, 1,58 + 3,04 + 6,96 + 3,42

= ( 1,58 + 3,42) + ( 3,04 + 6,96)

= 5 + 10

= 15

c, \(\dfrac{1}{2}\) + \(\dfrac{1}{3}\) + \(\dfrac{1}{5}\) + \(\dfrac{1}{6}\)

=  ( \(\dfrac{1}{2}\) + \(\dfrac{1}{3}\) + \(\dfrac{1}{6}\)) + 0,2

= 1 + 0,2

= 1,2 

a)

$127+246+273+354$

$=(127+273)+(246+354)$

$=400+600$

$=1000$

b)

$1,58+3,04+6,96+3,42$

$=(1,58+3,42)+(3,04+6,96)$

$=5+10$

$=15$

c)

$1/2+1/3+1/5+1/6$

$=(1/2+1/3+1/6)+1/5$

$=(3/6+2/6+1/6)+1/5$

$=6/6+1/5$

$=1+1/5$

$=5/5+1/5$

$=6/5$

= 3,42 x 25,7 + 3,42 x 16,8 - 3,42 x 12 - 3,42 x 21,5 +3,42 x 1

=3,42 x ( 25,7 + 16,8 -12 - 21,5 + 1 )

=3,42 x 10

=34,2

34,2 nhé

1a) \(\frac{10}{11}:\frac{11}{3}=\frac{10}{11}.\frac{3}{11}=\frac{30}{121}\)

b) \(3,42:0,75.8,4-6,8\)

\(=4,56.8,4-6,8=38,304-6,8=31,504\)

2a) \(\frac{21}{11}.\frac{22}{17}.\frac{68}{63}=\frac{21.22.68}{11.17.63}=\frac{7.3.2.11.17.4}{11.17.3.3.7}=\frac{2.4}{3}=\frac{8}{3}\)

b) \(\frac{5}{14}.\frac{7}{13}.\frac{26}{25}=\frac{5.7.26}{14.13.25}=\frac{5.7.13.2}{2.7.13.5.5}=\frac{1}{5}\)

\(\frac{10}{11}:1\frac{1}{3}\)

\(=\frac{10}{11}:\frac{4}{3}\)

\(=\frac{10}{11}\cdot\frac{3}{4}\)

\(=\frac{15}{22}\)

\(3,42:0,57\cdot8,4-6,8\)

\(=6\cdot8,4-6,8\)

\(=50,4-6,8\)

\(43,6\)

2.

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

\(=\frac{21\cdot22\cdot68}{11\cdot17\cdot63}\)

\(=\frac{21\cdot11\cdot2\cdot17\cdot4}{11\cdot17\cdot21\cdot3}\)

\(=\frac{̸21\cdot̸11\cdot2\cdot̸17\cdot4}{̸11\cdot̸17\cdot̸21\cdot3}\)

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

\(\frac{5}{14}\cdot\frac{7}{13}\cdot\frac{26}{25}\)

\(=\frac{5\cdot7\cdot26}{14\cdot13\cdot25}\)

\(=\frac{̸5\cdot̸7\cdot̸13\cdot2}{̸7\cdot2\cdot̸13\cdot̸5\cdot5}\)

\(=\frac{2}{10}\)