\(\dfrac{x-1}{5}=\dfrac{y-2}{3}=\dfrac{z-2}{2}=\dfrac{2y-4}{6}=\dfrac{x-1+2y-4-z+2}{5+6-2}=\dfrac{6-5}{9}=\dfrac{1}{9}\)

\(\Rightarrow\left\{{}\begin{matrix}9x-9=5\\9y-18=3\\9z-18=2\end{matrix}\right.\)

\(\Rightarrow\left\{{}\begin{matrix}x=\dfrac{14}{9}\\y=\dfrac{7}{3}\\z=\dfrac{20}{9}\end{matrix}\right.\)

Tham khảo

B

B

b

1)1/6 - - 5/6 = 1/6 + 5/6 = 1

2)6/13 - -14/39 = 6/13 + 14/39= 32/39

3)4/5 - 4/-18 = 4/5 + 4/18= 46/45

4)7/21 - 9/-36 = 7/21 + 9/36 = 7/12

5)-12/18 - -21/35  = -12/18 + 21/35 = -1/15

6)-3/21 - 6/42 = -2/7

7)-18/24 - 15/21 = -41/28

8)1/6 - 2/5 =-7/30

\(\dfrac{5\cdot4^{15}\cdot9^9-4\cdot3^{20}\cdot8^9}{5\cdot2^{29}\cdot9^{10}-7\cdot2^{29}\cdot27^6}\)

\(=\dfrac{5\cdot2^{30}\cdot3^{18}-2^2\cdot2^{27}\cdot3^{20}}{5\cdot2^{29}\cdot3^{20}-7\cdot2^{29}\cdot3^{18}}\)

\(=\dfrac{2^{29}\cdot3^{18}\left(5\cdot2-3^2\right)}{2^{29}\cdot3^{18}\left(5\cdot3^2-7\right)}\)

\(=\dfrac{10-9}{5\cdot9-7}=\dfrac{1}{38}\)

a, \(\dfrac{4x}{7}=\dfrac{1}{5}+\dfrac{2}{3}=\dfrac{3+10}{15}=\dfrac{13}{15}\Rightarrow60x=91\Leftrightarrow x=\dfrac{91}{60}\)

b, \(\dfrac{5}{7}:x=\dfrac{1}{6}+\dfrac{4}{5}=\dfrac{5+24}{30}=\dfrac{29}{30}\Leftrightarrow x=\dfrac{5}{7}:\dfrac{29}{30}=\dfrac{150}{203}\)

Bạn viết đề bằng công thức toán mọi người sẽ hỗ trợ tốt hơn chứ viết thế này khó hiểu quá.

\(-\dfrac{7}{8}\times\dfrac{16}{21}-\dfrac{5}{3}\times\left(-\dfrac{1}{2}\right)=-\dfrac{2}{3}+\dfrac{5}{6}=-\dfrac{4}{6}+\dfrac{5}{6}=\dfrac{1}{6}\)