1+2+3+4+5+6+7+8+9X2=1+2+3+4+5+6+7+8+18=54

1+2+3+4+5+6+7+8+9x2=1+2+3+4+5+6+7+8+18=54

120²³

tính khùng lun á bạn

=120²³

`3-4/5:1/3`

`=3-4/5xx3/1`

`=3-12/5`

`=15/5-12/5`

`=3/5`

`5/9xx2/7-3/7`

`=10/63-3/7`

`=10/63-27/63`

`=-17/63`

`12/8-3/4+3`

`=12/8-6/8+24/8`

`=30/8=15/4`

$3-4/5:1/3$

=3−4/5��3/1$=3-4/5xx3/1$

=3−12/5$=3-12/5$

=15/5−12/5$=15/5-12/5$

=3/5$=3/5$

5/9��2/7−3/7$5/9xx2/7-3/7$

=10/63−3/7$=10/63-3/7$

=10/63−27/63$=10/63-27/63$

=−17/63$=-17/63$

12/8−3/4+3$12/8-3/4+3$

=12/8−6/8+24/8$=12/8-6/8+24/8$

=30/8=15/4$=30/8=15/4$

$3-4/5:1/3$

=3−4/5��3/1$=3-4/5xx3/1$

=3−12/5$=3-12/5$

=15/5−12/5$=15/5-12/5$

=3/5$=3/5$

5/9��2/7−3/7$5/9xx2/7-3/7$

=10/63−3/7$=10/63-3/7$

=10/63−27/63$=10/63-27/63$

=−17/63$=-17/63$

12/8−3/4+3$12/8-3/4+3$

=12/8−6/8+24/8$=12/8-6/8+24/8$

=30/8=15/4$=30/8=15/4$

a) \(1678\cdot24+77\cdot1678-1678=1678\left(24+77-1\right)=167800\)

b) Ta có: \(\dfrac{2}{5}+\dfrac{4}{11}+\dfrac{3}{5}+\dfrac{18}{11}+\dfrac{1}{4}+\dfrac{1}{6}\)

\(=\left(\dfrac{2}{5}+\dfrac{3}{5}\right)+\left(\dfrac{4}{11}+\dfrac{18}{11}\right)+\dfrac{1}{4}+\dfrac{1}{6}\)

\(=3+\dfrac{1}{4}+\dfrac{1}{6}\)

\(=\dfrac{36}{12}+\dfrac{3}{12}+\dfrac{2}{12}=\dfrac{41}{12}\)

c) \(\dfrac{7}{9\cdot7}+\dfrac{7}{9\cdot4}-\dfrac{7}{9\cdot10}\)

\(=\dfrac{7}{9}\left(\dfrac{1}{7}+\dfrac{1}{4}-\dfrac{1}{10}\right)\)

\(=\dfrac{7}{9}\cdot\left(\dfrac{20}{140}+\dfrac{35}{140}-\dfrac{14}{140}\right)\)

\(=\dfrac{7}{9}\cdot\dfrac{41}{140}=\dfrac{41}{180}\)

5: \(=3-\dfrac{1}{4}+\dfrac{2}{3}-5+\dfrac{1}{3}+\dfrac{6}{5}-6+\dfrac{7}{4}-\dfrac{3}{2}\)

\(=3-5-6+\dfrac{-1}{4}+\dfrac{7}{4}+\dfrac{2}{3}+\dfrac{1}{3}+\dfrac{6}{5}-\dfrac{3}{2}\)

\(=-8+\dfrac{3}{2}+1+\dfrac{-3}{10}\)

\(=-7+\dfrac{15-3}{10}=-7+\dfrac{6}{5}=-\dfrac{29}{5}\)

6: \(=6-\dfrac{2}{3}+\dfrac{1}{2}-5-\dfrac{5}{3}+\dfrac{3}{2}-3+\dfrac{7}{3}-\dfrac{5}{2}\)

\(=6-5-3-\dfrac{2}{3}-\dfrac{5}{3}+\dfrac{7}{3}+\dfrac{1}{2}+\dfrac{3}{2}-\dfrac{5}{2}\)

\(=-2-\dfrac{1}{2}=-\dfrac{5}{2}\)

7: \(=\dfrac{5}{3}-\dfrac{3}{7}+9-2-\dfrac{5}{7}+\dfrac{2}{3}+\dfrac{8}{7}-\dfrac{4}{3}-10\)

\(=9-2-10+\dfrac{5}{3}+\dfrac{2}{3}-\dfrac{4}{3}+\dfrac{-3}{7}-\dfrac{5}{7}+\dfrac{8}{7}\)

=-3+1

=-2

8: \(=8-\dfrac{9}{4}+\dfrac{2}{7}+6+\dfrac{3}{7}-\dfrac{5}{4}-3-\dfrac{2}{4}+\dfrac{9}{7}\)

\(=8+6-3+\dfrac{2}{7}+\dfrac{3}{7}+\dfrac{9}{7}-1-\dfrac{2}{4}\)

\(=11+2-1-\dfrac{1}{2}\)

=11+1/2

=11,5

9/10

17/36

7/6

19/12

67/56

12/35

11/8

7/12

25/24

73/21

17/30

2

ok chưa bạn!

xàm??

.-. ?

spam à

= (1+1+1+1)+(2+2+2)+(3+3+3+3)+(4+4+4+4)+(5+5+5+5)+(6+6+6+6)+(7+7+7+7)+(8+8+8+8)+(9+9+9+9)+10
4 + 6 + 12 + 16 + 20 + 24 + 28 + 32 + 36 + 10 =
= 188

14dm5cm=14,5dm;3dm7cm=3,7dm

chu vi hình chữ nhật đó là:

(14,5+3,7)x2=36,4(dm)

ĐS:36,4dm

14 dm 5 cm = 14,5 dm 

3 dm 7 cm = 3,7 dm 

Chiều rộng HCN là :

14,5 - 3,7 = 10,8 ( dm )

chu vi HCN là :

( 14,5 + 10,8 ) x 2 = 50,6 ( dm )

ĐS:..

ban lam sai roi