Theo đề a - 2,8 = 7,7

=> a = 7,7 + 2,8 = 10,5

Đúng 100% luôn mình làm rồi

4,9 nha bạn 

CHÚC BẠN HỌC TỐT NHA!

= 7,7 chu ko phai la + 7,7

`=>B`

`|-6,3-x|>=0`

`=>A>=0+7,7=7`

Dấu "=" `<=>-6,3-x=0<=>x=-6,3`

\(1,0,75-\dfrac{2}{3}-0,5=\dfrac{3}{4}-\dfrac{2}{3}-\dfrac{1}{2}=\dfrac{9}{12}-\dfrac{8}{12}-\dfrac{1}{2}=\dfrac{1}{12}-\dfrac{1}{2}\)

\(=\dfrac{2}{24}-\dfrac{12}{24}=\dfrac{-10}{24}=\dfrac{-5}{12}\)

\(2,\dfrac{1}{5}-0,125-\dfrac{5}{4}=\dfrac{1}{5}-\dfrac{1}{8}-\dfrac{5}{4}=\dfrac{8}{40}-\dfrac{5}{40}-\dfrac{5}{4}=\dfrac{3}{40}-\dfrac{5}{4}\)

\(=\dfrac{3}{40}-\dfrac{50}{40}=\dfrac{-47}{40}\)

\(3,1,25-\dfrac{3}{4}+\dfrac{4}{3}=\dfrac{5}{4}-\dfrac{3}{4}+\dfrac{4}{3}=\dfrac{2}{4}+\dfrac{4}{3}=\dfrac{6}{12}+\dfrac{16}{12}=\dfrac{22}{12}=\dfrac{11}{6}\)

\(4,0,15-\dfrac{1}{4}+\dfrac{2}{5}=\dfrac{3}{20}-\dfrac{1}{4}+\dfrac{2}{5}=\dfrac{3}{20}-\dfrac{5}{20}+\dfrac{2}{5}=\dfrac{-2}{20}+\dfrac{2}{5}\)

\(=\dfrac{-2}{20}+\dfrac{8}{20}=\dfrac{6}{20}=\dfrac{3}{10}\)

\(5,5-3,4+\dfrac{1}{5}=\dfrac{5}{1}-\dfrac{17}{5}+\dfrac{1}{5}=\dfrac{25}{5}-\dfrac{17}{5}+\dfrac{1}{5}=\dfrac{25-17+1}{5}=\dfrac{9}{5}\)

\(6,\dfrac{1}{4}-0,3+\dfrac{4}{3}=\dfrac{1}{4}-\dfrac{3}{10}+\dfrac{4}{3}=\dfrac{10}{40}-\dfrac{12}{40}+\dfrac{4}{3}=\dfrac{-2}{40}+\dfrac{4}{3}\)

\(=\dfrac{-1}{20}+\dfrac{4}{3}=\dfrac{-3}{60}+\dfrac{80}{60}=\dfrac{77}{60}\)

\(7,0,2-3,25+4,7=\dfrac{1}{5}-\dfrac{13}{4}+\dfrac{47}{10}=\dfrac{4}{20}-\dfrac{65}{20}+\dfrac{47}{10}=\dfrac{-61}{20}+\dfrac{47}{10}\)

\(=\dfrac{-61}{20}+\dfrac{94}{20}=\dfrac{33}{20}=1,65\)

\(8,5,4+\dfrac{-7}{3}-\dfrac{-5}{7}=\dfrac{27}{5}+\dfrac{-7}{3}-\dfrac{-5}{7}=\dfrac{81}{15}+\dfrac{-35}{15}-\dfrac{-5}{7}\)

\(=\dfrac{46}{15}-\dfrac{-5}{7}=\dfrac{322}{105}-\dfrac{-75}{105}=\dfrac{397}{105}\)

\(9,\dfrac{-4}{2}+\dfrac{1}{3}-\dfrac{1}{4}=\dfrac{-12}{6}+\dfrac{2}{6}-\dfrac{1}{4}=\dfrac{-10}{6}-\dfrac{1}{4}=\dfrac{-5}{3}-\dfrac{1}{4}\)

\(=\dfrac{-20}{12}-\dfrac{3}{12}=\text{ }\dfrac{-23}{12}\)

\(10,5,4-1,5-\left(7,2-1\right)=3,9-6,2=-2,3\)

\(11,4,9-\left(1,5-7,7+3\right)=4,9-\left(-3,2\right)=8,1\)

\(12,7,8-4,7+\left(5,3-1,4\right)=3,1+3,9=7\)

\(14,\dfrac{1}{2}-0,4+\dfrac{1}{5}\text{=}0,5-0,4+0,2=0,3\)

\(15,4,2-\dfrac{4}{5}+\dfrac{1}{2}=4,2-0,8+0,5=3,9\)

12,3

\(7,7+2,3.2=7,7+4,6=12,3\)

12,3

gấp ạ mình đang cần

\(A=\dfrac{4}{5}\)

https://hoidap247.com/cau-hoi/2120972

tk

   7,7×9+7,7

= 7,7 x ( 9 + 1 )

= 7,7 x 10

= 77

Tính nhanh

7,7×9+7,7 

= 7,7 x (9+1)

= 7,7 x 10

= 77

# HOK TỐT #

=7,7x10=77

7/6 mình trắc chắn 100%

Trong các phân số 5/7,7/8,4/7,7/6,phân số lớn nhất là:

A. 5/7 

B. 7/8

C. 4/7

D. 7/6

\(\frac{7}{6}\) là đáp án đúng nhất

a) = 194970 + 4020 + 2010 = 201000

b)

= ( 1,1 + 9,9) + ( 2,2 + 8,8) + ( 3,3+7,7) + ( 4,4 + 6,6) + 4,5 + 6 + 1/2

= 10 + 10 + 10 + 10 + 4,5 + 6 + 1/2

= 51

  7,7 x 9 + 7,7

= 7,7 x (9+1)

= 7,7 x 10

= 77

\(7,7\cdot9+7,7=7,7\cdot\left(9+1\right)=7,7\cdot10=77\)

mik cũng gặp câu này mak ko biết trả lời