Tìm các cặp số nguyên x, y, z biết: - 4 8 = x - 10 = - 7 y = z - 4
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![](https://rs.olm.vn/images/avt/0.png?1311)
Xét : \(\frac{-4}{8}=\frac{x}{-10}\Leftrightarrow8x=40\Leftrightarrow x=5\)
\(\frac{-4}{8}=\frac{-7}{y}\Leftrightarrow-4y=-56\Leftrightarrow y=14\)
\(\frac{-4}{8}=\frac{z}{24}\Leftrightarrow-96=8z\Leftrightarrow z=-12\)
![](https://rs.olm.vn/images/avt/0.png?1311)
![](https://rs.olm.vn/images/avt/0.png?1311)
Giải:
\(\dfrac{-4}{8}=\dfrac{x}{-10}=\dfrac{-7}{y}=\dfrac{z}{-3}\)
\(\Rightarrow\dfrac{-4}{8}=\dfrac{x}{-10}\)
\(\Rightarrow x=\dfrac{-10.-4}{8}=5\)
\(\Rightarrow\dfrac{-4}{8}=\dfrac{-7}{y}\)
\(\Rightarrow y=\dfrac{-7.8}{-4}=14\)
\(\Rightarrow\dfrac{-4}{8}=\dfrac{z}{-3}\)
\(\Rightarrow z=\dfrac{-4.-3}{8}=\dfrac{3}{2}\)
![](https://rs.olm.vn/images/avt/0.png?1311)
a: \(\dfrac{-4}{8}=\dfrac{x}{-10}=\dfrac{-7}{y}=\dfrac{z}{-24}\)
=>\(\dfrac{x}{-10}=\dfrac{-7}{y}=\dfrac{z}{-24}=\dfrac{-1}{2}\)
=>\(\left\{{}\begin{matrix}x=\left(-10\right)\cdot\dfrac{\left(-1\right)}{2}=5\\y=\dfrac{-7\cdot2}{-1}=14\\z=\dfrac{-24\cdot\left(-1\right)}{2}=\dfrac{24}{2}=12\end{matrix}\right.\)
b: \(\dfrac{-3}{6}=\dfrac{x}{-2}=\dfrac{-18}{y}=\dfrac{-z}{24}\)
=>\(\dfrac{x}{-2}=\dfrac{-18}{y}=\dfrac{z}{-24}=\dfrac{-1}{2}\)
=>\(\dfrac{x}{2}=\dfrac{18}{y}=\dfrac{z}{24}=\dfrac{1}{2}\)
=>\(x=2\cdot\dfrac{1}{2}=1;y=18\cdot\dfrac{2}{1}=36;z=\dfrac{24}{2}=12\)
![](https://rs.olm.vn/images/avt/0.png?1311)
\(-\frac{4}{8}=-\frac{1}{2}=\frac{5}{-10}=\frac{x}{-10}=-\frac{7}{14}=-\frac{7}{y}=\frac{12}{-24}=\frac{z}{-24}\)
=> x = 5; y = 14; z = 12.
![](https://rs.olm.vn/images/avt/0.png?1311)
Bài 1
a) (x + 3)(x + 2) = 0
x + 3 = 0 hoặc x + 2 = 0
*) x + 3 = 0
x = 0 - 3
x = -3 (nhận)
*) x + 2 = 0
x = 0 - 2
x = -2 (nhận)
Vậy x = -3; x = -2
b) (7 - x)³ = -8
(7 - x)³ = (-2)³
7 - x = -2
x = 7 + 2
x = 9 (nhận)
Vậy x = 9