
Hãy nhập câu hỏi của bạn vào đây, nếu là tài khoản VIP, bạn sẽ được ưu tiên trả lời.


\(\frac{15}{29}+\frac{-9}{31}+\frac{-7}{8}+\frac{14}{29}-\frac{-22}{31}=\frac{15}{29}+\frac{14}{29}+\left(\frac{-9}{31}+\frac{-22}{31}\right)-\frac{-7}{8}=0-\frac{-7}{8}=\frac{7}{8}\)

\(=\frac{22}{25}\cdot\frac{5}{11}-\frac{22}{25}\cdot\frac{8}{9}-\frac{8}{9}\cdot\frac{27}{4}+\frac{8}{9}\cdot\frac{22}{25}\)
\(=\frac{2}{5}-6=-\frac{28}{5}\)

\(=\frac{11}{14}-\frac{8}{19}+\frac{3}{14}-\frac{8}{19}\)
\(=\left(\frac{11}{14}+\frac{3}{14}\right)-\left(\frac{8}{19}+\frac{8}{19}\right)\)\(=1-\frac{16}{19}=\frac{3}{19}\)

1, Tính tổng:
\(C=\frac{5}{7}\cdot\frac{5}{11}+\frac{5}{7}\cdot\frac{2}{11}-\frac{5}{7}\cdot\frac{14}{11}\)
\(=\frac{5}{7}\cdot\left(\frac{5}{11}+\frac{2}{11}-\frac{14}{11}\right)=\frac{5}{7}\cdot\frac{-7}{11}=\frac{-5}{11}\)
2, Tìm x:
\(x+\frac{5}{5\cdot9}+\frac{4}{9\cdot13}+\frac{4}{13\cdot17}+...+\frac{4}{41\cdot45}=\frac{-37}{45}\)
\(\Rightarrow x+\frac{1}{5}-\frac{1}{9}+\frac{1}{9}-\frac{1}{13}+\frac{1}{13}-\frac{1}{17}+...+\frac{1}{41}-\frac{1}{45}=\frac{-37}{45}\)
\(\Rightarrow x+\frac{1}{5}-\frac{1}{45}=\frac{-37}{45}\Rightarrow x+\frac{9}{45}-\frac{1}{45}=\frac{-37}{45}\)
\(\Rightarrow x+\frac{8}{45}=\frac{-37}{45}\Rightarrow x=\frac{-37}{45}-\frac{8}{45}=\frac{-45}{45}=-1\)
- Các bài tìm x còn lại bạn cứ theo trình tự thực hiện phép tính mà làm nhé!
\(C=\frac{5}{7}\cdot\frac{5}{11}+\frac{5}{7}\cdot\frac{2}{11}-\frac{5}{7}\cdot\frac{14}{11}\)
\(=\frac{5}{7}\cdot\left(\frac{5}{11}+\frac{2}{11}-\frac{14}{11}\right)\)
\(=\frac{5}{7}\cdot-\frac{7}{11}\)
\(=-\frac{5}{11}\)

TA có \(-\frac{7}{8}-x=-\frac{5}{12}\)
<=>\(x=-\frac{7}{8}+\frac{5}{12}\)
<=>\(x=-\frac{21}{24}+\frac{10}{24}\)
<=>\(x=-\frac{11}{24}\)
Vậy \(x=-\frac{11}{24}\)
Ta có \(x+\frac{5}{11}=-\frac{23}{22}\)
<=>\(x=-\frac{23}{22}-\frac{5}{11}\)
<=>\(x=-\frac{23}{22}-\frac{10}{22}\)
<=>\(x=-\frac{33}{22}\)
<=>\(x=\frac{-3}{2}\)
Vậy \(x=-\frac{3}{2}\)

\(\frac{x-1}{6}=\frac{1}{6}\Leftrightarrow6\left(x-1\right)=6\Leftrightarrow6x-6=6\Leftrightarrow6x=12\Leftrightarrow x=2\)
\(\frac{x-2}{5}=\frac{8}{10}=\frac{4}{5}\Leftrightarrow5\left(x-2\right)=4.5=20\Leftrightarrow5x-10=20\Leftrightarrow5x=30\Leftrightarrow x=6\)
\(\frac{x-1}{8}=\frac{1}{2}\Leftrightarrow2\left(x-1\right)=8\Leftrightarrow2x-2=8\Leftrightarrow2x=10\Leftrightarrow x=5\)
\(\text{ câu 1 mk nghĩ là so sánh chứ nhỉ?}\)

mik ko chép lại đề, mik làm luôn:
a) x - \(\frac{31}{36}=\frac{-13}{38}\)
x = \(\frac{-13}{18}+\frac{31}{36}\)
\(x=\frac{5}{36}\)
b)\(2-x-\frac{3}{7}=\frac{9}{-21}\)
\(\frac{11}{7}-x=\frac{3}{7}\)
x = \(\frac{11}{7}-\frac{3}{7}\)
x = 8/7
c) x + 3/11 = 23/44
x = 23/44 - 3/11
x = 1/4
d) \(\frac{1}{12}-x=\frac{-11}{9}\)
x = \(\frac{1}{12}+\frac{11}{9}\)
x = 47/36
e) \(x-\frac{2}{3}=\frac{-17}{3}\)
x= -17/3 + 2/3
x = -5
f) \(x-\frac{1}{2}=\frac{11}{4}.\frac{3}{11}\)
x - 1/2 = 3/4
x = 3/4 + 1/2
x = 5/4
g) \(2x+\frac{3}{8}=\frac{-21}{32}.\frac{4}{7}\)
2x + 3/8 = -3 / 8
2x = -3/8 - 3/8
2x = -9/8
x = -9/8.1/2
x = -9/16
h) x - \(\frac{x}{3}=\frac{3}{57}.\frac{19}{12}\)
x - \(\frac{x}{3}=\frac{1}{12}\)
x = \(\frac{1}{12}+\frac{x}{3}\)
x = \(\frac{1+4x}{12}\)
=> 12x = 1+4x
12x - 4x = 1
8x = 1
x = 1/8

b/ Ta có
\(A-B=\frac{3}{8^3}+\frac{7}{8^4}-\frac{7}{8^3}-\frac{3}{8^4}\)
\(=\frac{4}{8^4}-\frac{4}{8^3}< 0\)
Vậy A < B
c/ Đặt \(10^7=a\)thì ta có
\(A=\frac{a+5}{a-8};B=\frac{10a+6}{10a-7}\)
Giả sử A>B thì ta có
\(\frac{a+5}{a-8}>\frac{10a+6}{10a-7}\)
\(\Leftrightarrow10a^2+43a-35>10a^2-574a-348\)
\(\Leftrightarrow617a+313>0\)(đúng)
Vậy A>B
c/ Đặt \(10^{1991}=a\)thì ta có
\(A=\frac{10a+1}{a+1};B=\frac{100a+1}{10a+1}\)
Giả sử A>B thì ta có
\(\frac{10a+1}{a+1}>\frac{100a+1}{10a+1}\)
\(\Leftrightarrow\left(10a+1\right)^2>\left(100a+1\right)\left(a+1\right)\)
\(\Leftrightarrow-81a>0\)(sai)
Vậy A < B
a/ Thì quy đồng là ra nhé
a,b,c,d giống nhau cùng nhân A và B với 1 số nào đấy tách ra r` so sạmh

Bài giải
a, \(\frac{7}{12}+\frac{5}{6}+\frac{1}{4}-\frac{3}{7}-\frac{5}{12}\)
\(=\left(\frac{7}{12}-\frac{5}{12}+\frac{5}{6}+\frac{1}{4}\right)-\frac{3}{7}=\left(\frac{7}{12}-\frac{5}{12}+\frac{10}{12}+\frac{3}{12}\right)-\frac{3}{7}=\frac{5}{4}-\frac{3}{7}=\frac{23}{28}\)
b, \(\frac{11\cdot3^{22}\cdot3^7-9^{15}}{\left(2\cdot3^{14}\right)^2}=\frac{11\cdot3^{29}-3^{30}}{2^2\cdot3^{28}}=\frac{3^{29}\left(11-3\right)}{3^{28}\cdot4}=\frac{3\cdot8}{4}=6\)
\(\frac{14}{-11}+\frac{8}{22}\)
\(=\frac{-14}{11}+\frac{8}{22}\)
\(=\frac{-308}{242}+\frac{88}{242}\)
\(=\frac{-220}{242}\)
\(=\frac{-10}{11}\)
**Trả lời:
\(\frac{14}{-11}+\frac{8}{22}\)
\(=\frac{-14}{11}+\frac{8}{22}\)
\(=\frac{-14}{11}+\frac{4}{11}\)
\(=\frac{-10}{11}\)