12 xe bạn nhé

\(530\div45\approx12\)

Vậy cần 12 xe

\(a,2.2.2.2.2=2^5\\ b,2.3.6.6.6=6.6.6.6=6^4\\ c,4.4.5.5.5=4^2.5^3\)

\(a.=2^5\)

\(b.=6.6.6.6=6^4\)

\(c.=4^2.5^3\)

\(\dfrac{15}{29}-\dfrac{8}{7}+\dfrac{16}{14}+\dfrac{14}{29}-\dfrac{3}{8}\\ =\left(\dfrac{15}{29}+\dfrac{14}{29}\right)+\left(\dfrac{16}{14}-\dfrac{8}{7}\right)-\dfrac{3}{8}\\ =\dfrac{29}{29}+\left(\dfrac{8}{7}-\dfrac{8}{7}\right)-\dfrac{3}{8}\\ =1-\dfrac{3}{8}=\dfrac{5}{8}\)

`15/29 - 8/7 + 16/14 + 14/29 - 3/8`

`=15/29 - 8/7 + 8/7 + 14/29 - 3/8`

`=(15/29 + 14/29) + (-8/7 + 8/7)- 3/8`

`=29/29 + 0 - 3/8`

`=1-3/8`

`=8/8 - 3/8`

`=5/8`

Gọi 2 số đó là : `3k+1;3k+2` ( `k\in Z` )

Tổng 2 số là : 

`3k+1+3k+2=6k+3=3(3k+1)` \(⋮3\)

Gọi 2 số đó là : `3k+1;3k+2` ( `k\in Z` )

Tổng 2 số là :

`3k+1+3k+2=6k+3=3(2k+1)` \(⋮3\)

a+(a+1)+(a+2)+(a+3)

=> 4a + 6

4a chia hết cho 4

6 không chia hết cho 4

Vậy tổng của 4 số tự nhiên liên tiếp không chia hết cho 4

Cảm ơn bn nhé!

\(\dfrac{1}{2}-\dfrac{1}{2}:x=\dfrac{3}{4}\\ =>\dfrac{1}{2}:x=\dfrac{1}{2}-\dfrac{3}{4}=-\dfrac{1}{4}\\ =>x=\dfrac{1}{2}:\left(-\dfrac{1}{4}\right)=-2\)

`1/2 - 1/2 : x =3/4`

`1/2 : x = 1/2 -3/4`

`1/2:x=2/4-3/4`

`1/2:x=-1/4`

`x=1/2:(-1/4)`

`x=1/2.(-4)`

`x=-2`

\(\overline{abba}=\overline{a00a}+\overline{bb0}\\ =a\times1000+a+b\times100+b\times10\\ =a\times1001+b\times110\\ =11\times\left(a\times91+b\times10\right)⋮11\)

`0,5 + 1/3 + 0,4 + 5/7 + 1/6 - 4/35`

`=1/2 + 1/3 + 2/5 + 5/7 + 1/6 - 4/35`

`=(1/2 + 1/3 + 1/6) +(2/5+5/7-4/35)`

`=(3/6+2/6+1/6)+(14/35 +25/35-4/35)`

`=6/6 + 35/35`

`=1+1`

`=2`