Tìm các số nguyên x , y , z biết A , x/35 = -6/9 = 18/z = -3/7 B , x + 5/ -25 = -4/x+5 20/09/2021 Bởi Margaret Tìm các số nguyên x , y , z biết A , x/35 = -6/9 = 18/z = -3/7 B , x + 5/ -25 = -4/x+5
a) Ta có: ` +) x/35 = -6/9` => `x = -6/9. 35` => `x= -70/3` `+) 18/z = -3/7` => `z= 18 : (-3/7)` => `z= 18. (-7/3)` => `z= -42` Vậy `x= -70/3` ; `z= -42` b) `(x+5)/-25 = -4/(x+5)` => `(x+5)(x+5) = -4.(-25)` => `(x+5)^2 = 100` => \(\left[ \begin{array}{l}(x+5)^2=10^2\\(x+5)^2=(-10)^2\end{array} \right.\) => \(\left[ \begin{array}{l}x+5=10\\x+5=-10\end{array} \right.\) => \(\left[ \begin{array}{l}x= 5\\x=-15\end{array} \right.\) Vậy `x= 5` hoặc `x= -15` Bình luận
Tham khảo `a) \frac{x}{35}=\frac{-6}{9}` `⇒x=\frac{-6.35}{9}=\frac{-70}{3}` Có `\frac{18}{z}=\frac{-3}{7}(z \ne 0)` `⇒z=\frac{18.7}{-3}=-42` `b) \frac{x+5}{-25}=\frac{-4}{x+5}` `⇒(x+5)^2=-25.(-4)` `⇒(x+5)^2=100` `⇒x+5=±10` `⇒`\(\left[ \begin{array}{l}x+5=10\\x+5=-10\end{array} \right.\) `⇒`\(\left[ \begin{array}{l}x=5\\x=-15\end{array} \right.\) Vậy `x=5` hoặc `x=-15` `\text{©CBT}` Bình luận
a) Ta có:
` +) x/35 = -6/9`
=> `x = -6/9. 35`
=> `x= -70/3`
`+) 18/z = -3/7`
=> `z= 18 : (-3/7)`
=> `z= 18. (-7/3)`
=> `z= -42`
Vậy `x= -70/3` ; `z= -42`
b) `(x+5)/-25 = -4/(x+5)`
=> `(x+5)(x+5) = -4.(-25)`
=> `(x+5)^2 = 100`
=> \(\left[ \begin{array}{l}(x+5)^2=10^2\\(x+5)^2=(-10)^2\end{array} \right.\)
=> \(\left[ \begin{array}{l}x+5=10\\x+5=-10\end{array} \right.\)
=> \(\left[ \begin{array}{l}x= 5\\x=-15\end{array} \right.\)
Vậy `x= 5` hoặc `x= -15`
Tham khảo
`a) \frac{x}{35}=\frac{-6}{9}`
`⇒x=\frac{-6.35}{9}=\frac{-70}{3}`
Có `\frac{18}{z}=\frac{-3}{7}(z \ne 0)`
`⇒z=\frac{18.7}{-3}=-42`
`b) \frac{x+5}{-25}=\frac{-4}{x+5}`
`⇒(x+5)^2=-25.(-4)`
`⇒(x+5)^2=100`
`⇒x+5=±10`
`⇒`\(\left[ \begin{array}{l}x+5=10\\x+5=-10\end{array} \right.\)
`⇒`\(\left[ \begin{array}{l}x=5\\x=-15\end{array} \right.\)
Vậy `x=5` hoặc `x=-15`
`\text{©CBT}`