Đề đúng là: -12....nhé!

-12.(x - 5) + 7.(3 - x) = 5

=> -12x + 60 + 21 - 7x = 5

=> -12x - 7x = 5 - 21 - 60

=> -19x = -76

=> x = 4

7/5;7/6 và 3/2

Đúng hỏi chị google ý chứ có ai biết,chỉ có chị ý biết mọi thứ haha 

\(3x\left(2x+1\right)=0\)

\(\Rightarrow\orbr{\begin{cases}2x+1=0\\3x=0\end{cases}}\)

\(\Rightarrow\orbr{\begin{cases}2x=-1\\x=0\end{cases}}\)

\(\Rightarrow\orbr{\begin{cases}x=-\frac{1}{2}\\x=0\end{cases}}\)

\(\frac{\frac{6}{5}+\frac{6}{35}-\frac{6}{125}-\frac{6}{2009}-\frac{6}{2011}}{\frac{7}{5}+\frac{7}{35}-\frac{7}{125}-\frac{7}{2009}-\frac{7}{2011}}\)

\(=\frac{6.(\frac{1}{5}+\frac{1}{35}-\frac{1}{125}-\frac{1}{2009}-\frac{1}{2011})}{7.(\frac{1}{5}+\frac{1}{35}-\frac{1}{125}-\frac{1}{2009}-\frac{1}{2011})}\)

\(=\frac{6}{7}\)

Tìm x

\(a,3x(2x+1)=0\)

\(\Rightarrow\hept{\begin{cases}3x=0\\2x+1=0\end{cases}}\)

\(\Rightarrow\hept{\begin{cases}x=0\\x=\frac{-1}{2}\end{cases}}\)

Vậy \(x=0\)hoặc \(x=\frac{-1}{2}\)

\(b.\frac{2}{3}-\frac{1}{3}(x-\frac{3}{2})-\frac{1}{2}(2x+1)=5\)

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

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

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

\(\frac{4}{3}x=\frac{-13}{3}\)

\(x=\frac{-13}{3}\div\frac{4}{3}\)

\(x=\frac{-13}{4}\)

Chúc ban học tốt

\(\frac{\frac{6}{5}+\frac{6}{35}-\frac{6}{125}-\frac{6}{2009}-\frac{6}{2011}}{\frac{7}{5}+\frac{7}{35}-\frac{7}{125}-\frac{7}{2009}-\frac{7}{2011}}\)

\(=\frac{6.\left(\frac{1}{5}+\frac{1}{35}-\frac{1}{125}-\frac{1}{2009}-\frac{1}{2011}\right)}{7.\left(\frac{1}{5}+\frac{1}{35}-\frac{1}{125}-\frac{1}{2009}-\frac{1}{2011}\right)}=\frac{6}{7}\)

Tìm x

a)bạn tự làm vì nó rất dễ nha

b)\(\frac{2}{3}-\frac{1}{3}.\left(x-\frac{3}{2}\right)-\frac{1}{2}.\left(2x+1\right)=5\)

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

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

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

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

\(\left(\frac{1}{3}-1\right)x=5+1+\frac{2}{3}\)

\(\frac{-2}{3}x=6+\frac{2}{3}\)

\(\frac{-2}{3}x=\frac{20}{3}\)

\(x=\frac{20}{3}:\left(\frac{-2}{3}\right)\)

\(x=\frac{20}{3}.\left(\frac{3}{-2}\right)\)

x=-10

Vậy x=-10

Chúc bạn học tốt

\(a,\dfrac{3}{4}:\dfrac{6}{x}=\dfrac{5}{4}\\ \dfrac{6}{x}=\dfrac{3}{4}:\dfrac{5}{4}\\ \dfrac{6}{x}=\dfrac{3}{5}\\ x=6:\dfrac{3}{5}\\ x=10\\ b,\left(x+\dfrac{7}{4}\right)\times\dfrac{2}{3}=6\\ x+\dfrac{7}{4}=6:\dfrac{2}{3}\\x+\dfrac{7}{4}=9\\ x=9-\dfrac{7}{4}\\ x=\dfrac{29}{4}\)

giúp mình đi, sao dạo này ít ngừi giúp qué zại

a) \(\dfrac{3}{4}\div\dfrac{6}{x}=\dfrac{5}{4}\)

            \(\dfrac{6}{x}=\dfrac{3}{4}\div\dfrac{5}{4}\)

            \(\dfrac{6}{x}=\dfrac{3}{5}\)

            \(x=\left(6\div3\right)\times5\)

           \(x=10\)

b) \(\left(x+\dfrac{7}{4}\right)\times\dfrac{2}{3}=6\)

     \(x+\dfrac{7}{4}=6\div\dfrac{2}{3}\)

     \(x+\dfrac{7}{4}=9\)

     \(x=9-\dfrac{7}{4}\)

    \(x=\dfrac{29}{4}\)

\(\dfrac{5}{7}=\dfrac{5\times3}{7\times3}=\dfrac{15}{21};\dfrac{6}{21}\)

\(\dfrac{20}{28}=\dfrac{20:4}{28:4}=\dfrac{5}{7};\dfrac{5}{7}\)

5/7=15/21

6/21 giữ nguyên

5/7=20/28 

20/28 giữ nguyên

5/7 và 6/21

mẫu số chung: 7

giữ nguyên \(\dfrac{5}{7}\)

\(\dfrac{6}{21}=\dfrac{6:3}{21:3}=\dfrac{2}{7}\)

5/7 và 20/28

mẫu số chung: 7

giữ nguyên \(\dfrac{5}{7}\)

\(\dfrac{20}{28}=\dfrac{20:4}{28:4}=\dfrac{5}{7}\)

câu trả lời của mk là :

1 + 2 + 3 + 4 + 5 + 6 + 7 + 8 + 9 + 2 = 43

~~~~ hok tốt ~~~~

1 + 2 + 3 + 4 + 5 + 6 + 7 + 8 + 9 + 2 

= 47

-chúc bạn học tốt.

Kết quả là : 47 

Mình nhanh nhất nhé !

a, 1+2+3+4+5+6+7+8+9

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

= 10+10+10+10+5 = 45

b, 1,1+2,2+3,3+4,4+5,5+6,6+7,7+8,8+9,9

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

= 11+11+11+11+5,5

= 11*4 + 5,5

= 44+5,5 = 49,5 

1+2+3+4+5+6+7+8+9=45

1,1+2,2+3,3+4,4+5,5+6,6+7,7+8,8+9,9=49,5

a)(1+9)+(2+8)+(3+7)+(4+6)+5=10+10+10+10+5=45

b)(1,1+9,9)+(2,2+8,8)+(3,3+7,7)+(4,4+6,6)+5,5=11+11+11+11+5,5=49,5