\(\frac{63}{5}\)

x+3.1=15.7

x=12.6

tik nha

63/5 duyệt đi

\(x+\frac{31}{10}=14,5+\frac{12}{10}\)

\(x+\frac{31}{10}=\frac{29}{2}+\frac{12}{10}\)

\(x+\frac{31}{10}=\frac{157}{10}\)

\(x=\frac{157}{10}-\frac{31}{10}\)

\(x=\frac{63}{5}\)

Học tốt #

\(x+\frac{31}{10}=14,5+\frac{12}{10}\)

\(\Rightarrow x+\frac{31}{10}=\frac{157}{10}\)

\(\Rightarrow x=\frac{157}{10}-\frac{31}{10}\)

\(\Rightarrow x=\frac{63}{5}\)

Vậy  \(x=\frac{63}{5}\)

_Chúc bạn học tốt_

x+31/10=14,5+12/10

x+31/10=29/2 + 12 /10

x+31/10=145/10+12/10

x+31/10=157/10

x=157/10-31/10

x=63/5

Vậy x=63/5

A, 11/12

B, 12,6

a,

x- 7/12 = 1/3

x = 1/3 + 7/12

x = 11/12

b,

x + 31/10 = 14,5

x = 14,5 - 31/10

x = 57/5

\(a,\\ x=\dfrac{1}{3}+\dfrac{7}{12}=\dfrac{11}{12}\\ b,\\ x+\dfrac{31}{10}=\dfrac{157}{10}\\ x=\dfrac{157}{10}-\dfrac{31}{10}=\dfrac{63}{5}\)

\(2x+\frac{7}{6}+\frac{13}{12}+\frac{21}{20}+\frac{31}{30}+\frac{43}{42}+\frac{57}{56}+\frac{73}{72}+\frac{91}{90}=10\)
=> \(2x+\frac{6+1}{6}+\frac{12+1}{12}+....+\frac{90+1}{90}=10\)
=> \(2x+\frac{1}{6}+\frac{1}{12}+\frac{1}{20}+...+\frac{1}{90}+10=10\)
=> \(2x+\frac{1}{6}+\frac{1}{12}+\frac{1}{20}+...+\frac{1}{90}=0\)
=>\(2x+\frac{1}{2.3}+\frac{1}{3.4}+\frac{1}{4.5}+...+\frac{1}{9.10}=0\)
=>\(2x+\frac{1}{2}-\frac{1}{3}+\frac{1}{3}-\frac{1}{4}+...+\frac{1}{9}-\frac{1}{10}=0\)
=> \(2x-\frac{1}{10}=0\)
=>2x=\(\frac{1}{10}\)=> x=1/20
 

mình có bị nhầm chỗ dấu suy ra thứ 3. đáng lẽ ra biểu thức đó cộng 8 chứ k phải cộng 10 do mình sơ ý nên bạn hãy sủa lại chỗ ấy

đây nhá tại đánh máy lâu quá nên gửi hình ^^

a) \(14:\frac{0,4x+0,6}{x}=7\)

\(\frac{0,4x+0,6}{x}=2\)

0,4x + 0,6 = 2.x

2x - 0,4x = 0,6

1,6x = 0,6

x = 0,375

b) \(\left(160\%+\frac{2}{3}x-x\right).12=660\)

\(\left(160\%+\frac{2}{3}x-x\right)=55\)

\(x\left(\frac{2}{3}-1\right)=53,4\)

\(-\frac{1}{3}x=\frac{267}{5}\)

\(x=\frac{267}{5}.\frac{3}{-1}\)

\(x=-160,2\)

c) \(1:\frac{1.2.3.4.....31}{2.2.2.3.2.4.....2.32}=2^x\)

\(1:\frac{1.2.3.4.....31}{2^{31}.2.3.4.....31.2^5}=2^x\)

\(1:\frac{1}{2^{36}}=2^x\)

\(2^{36}=2^x\)

\(x=36\)

\(x\cdot3\frac{1}{10}=\left(x+8\right)\cdot\frac{31}{12}\)

\(x\cdot\frac{31}{10}=x\cdot\frac{31}{12}+8\cdot\frac{31}{12}\)

\(x\cdot\frac{31}{10}-8\cdot\frac{31}{12}=x\cdot\frac{31}{12}\)

\(\frac{62}{3}=x\cdot\frac{31}{10}-x\cdot\frac{31}{12}=x\left(\frac{31}{10}-\frac{31}{12}\right)\)

\(\frac{62}{3}=x\cdot\frac{161}{60}\)

\(x=\frac{62}{3}:\frac{161}{60}=\frac{62\cdot60}{3\cdot161}\)

Phần còn lại bạn tính giúp mình nha!

Ta có: \(\frac{1}{2.2}.\frac{2}{2.3}.\frac{3}{2.4}.\frac{4}{2.5}.\frac{5}{2.6}.......\frac{30}{2.31}.\frac{31}{64}=4^x\)

\(\frac{1}{2^{30}.64}=4^x\Leftrightarrow4^x.2^{30}.2^6=1\)

\(\Leftrightarrow2^{2x+36}2^0\)

\(\Leftrightarrow2x+36=0\)

\(\Leftrightarrow2x=-36\)

\(\Leftrightarrow x=-18\)

Vậy ........

$4^x.64=1$\(\frac{1}{4}.\frac{2}{6}.\frac{3}{8}.\frac{4}{10}.\frac{5}{12}.....\frac{30}{62}.\frac{31}{64}=4^x\)

\(\Leftrightarrow\frac{1}{2.2}.\frac{2}{2.3}.\frac{3}{2.4}.\frac{4}{2.5}.\frac{5}{2.6}.....\frac{30}{2.31}.\frac{31}{2.32}=4^x\)

\(\Leftrightarrow\frac{1}{2}\left(\frac{1}{2}.\frac{2}{3}.\frac{3}{4}.\frac{4}{5}.\frac{5}{6}.....\frac{30}{31}.\frac{31}{32}\right)=4^x\)

\(\Leftrightarrow\frac{1}{2}.\frac{1.2.3.4.5.....30.31}{2.3.4.5.6.....31.32}=4^x\)

\(\Leftrightarrow\frac{1}{2}.\frac{1}{32}=4^x\)

\(\Leftrightarrow4^x=\frac{1}{64}\)

\(\Leftrightarrow4^x.64=1\)

\(\Leftrightarrow4^x.4^3=1\Leftrightarrow4^{x+3}=4^0\Leftrightarrow x+3=0\Leftrightarrow x=-3\)

Vậy x = -3

\(\frac{1}{4}.\frac{2}{6}.\frac{3}{8}.\frac{4}{10}.\frac{5}{12}...\frac{30}{62}.\frac{31}{64}=4^x\)

\(\Leftrightarrow\frac{1}{2.2}.\frac{2}{2.3}.\frac{3}{2.4}.\frac{4}{2.5}.\frac{5}{2.6}...\frac{30}{2.31}.\frac{31}{2.32}=4^x\)

\(\Leftrightarrow\frac{1.2.3.4.5...30.31}{2.2.2.3.2.4.2.5.2.6...2.31.2.32}=4^x\)

\(\Leftrightarrow\frac{2.3.4.5...30.31}{2^{31}.32.\left(2.3.4.5...31\right)}=4^x\)

\(\Leftrightarrow\frac{1}{2^{31}.2^5}=4^x\)

\(\Leftrightarrow\frac{1}{2^{36}}=4^x\)

\(\Leftrightarrow\frac{1}{4^{18}}=4^x\)

\(\Leftrightarrow x=-18\)

\(\frac{1}{4}.\frac{2}{6}.\frac{3}{8}.\frac{4}{10}.\frac{5}{12}.....\frac{30}{62}.\frac{31}{64}=2^x\)

=>\(\frac{1}{2.2}.\frac{2}{2.3}.\frac{3}{2.4}.\frac{4}{2.5}.\frac{5}{2.6}....\frac{30}{2.31}.\frac{31}{2.32}=2^x\)

=>\(\frac{1.2.3.4.5....30.31}{2.2.2.3.2.4.2.5.2.6...2.31.2.32}=2^x\)

=>\(\frac{2.3.4.5...30.31}{2^{31}.32.\left(2.3.4.5...31\right)}=2^x\)

=>\(\frac{1}{2^{31}.2^5}=2^x\)

=>\(\frac{1}{2^{36}}=2^x\)

=> x=36

Vậy x=36

Chúc bn học tốt nhé!