Tham khảo:

Bạn ơi bạn kiểm tra lại đề đi, đê sai rồi bạn ạ.

`27/81=(27:27)/(81:27)=1/3`

`57/76=(57:19)/(76:19)=3/4`

`35/84=(35:7)/(84:7)=5/12`

`MSC:12`

`1/3=(1xx4)/(3xx4)=4/12`

`3/4=(3xx3)/(4xx3)=9/12`

`5/12` giữ nguyên

\(\dfrac{27}{81}=\dfrac{1}{3}\); \(\dfrac{57}{76}=\dfrac{3}{4}\); \(\dfrac{35}{84}=\dfrac{5}{12}\)

\(\dfrac{1}{3}=\dfrac{4}{12}\)

\(\dfrac{3}{4}=\dfrac{9}{12}\)

Giữa nguyên 5/12

a, 75 – 27 + 13 = 51 ( sai vì 75 – 27 + 13 = 61)

b, 76 – 27 + 13 = 62 ( đúng vì 76 – 27 + 13 = 62)

Tính.

a) 50 + 18 – 45 = 68 - 45 = 23                              b) 76 – 56 + 27 = 20 + 27 = 47

a) \(-\left(76-35+15\right)+\left[18-27+\left(-17\right)\right]\)

\(=-76+35+15+18-27-17\)

\(=-52\)

b) \(167+\left[127-235-\left(-16\right)\right]+\left(-67\right)\)

\(=167+127-235+16-67\)

\(=8\)

c) \(\left(-19\right)+165-\left[27+\left(-21\right)-\left(+72\right)\right]\)

\(=\left(-19\right)+165-27+21+72\)

\(=212\)

d) \(89.\left(-2\right)+\left[20+\left(-2\right).\left(-5\right)-85\right]\)

\(=\left(-178\right)+\left(20+10-85\right)\)

\(=\left(-178\right)+20+10-85\)

\(=-233\)

a,

\(\frac{5-2x}{3}=\frac{4x-1}{-5}\)

-5(5-2x) = 3(4x-1)

-25 + 10x = 12x - 3

10x - 12x = -3 + 25

-2x = 22

x= -11

Nhân chéo như trên rồi tự làm nha

Học tốt~