Xét : \(\frac{-4}{8}=\frac{x}{-10}\Leftrightarrow8x=40\Leftrightarrow x=5\)

\(\frac{-4}{8}=\frac{-7}{y}\Leftrightarrow-4y=-56\Leftrightarrow y=14\)

\(\frac{-4}{8}=\frac{z}{24}\Leftrightarrow-96=8z\Leftrightarrow z=-12\)

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\(y=\frac{1}{x^2+\sqrt{x}}\)

x=5, y=49, z=12

Giải:

\(\dfrac{-4}{8}=\dfrac{x}{-10}=\dfrac{-7}{y}=\dfrac{z}{-3}\) 

\(\Rightarrow\dfrac{-4}{8}=\dfrac{x}{-10}\) 

\(\Rightarrow x=\dfrac{-10.-4}{8}=5\) 

\(\Rightarrow\dfrac{-4}{8}=\dfrac{-7}{y}\) 

\(\Rightarrow y=\dfrac{-7.8}{-4}=14\) 

\(\Rightarrow\dfrac{-4}{8}=\dfrac{z}{-3}\) 

\(\Rightarrow z=\dfrac{-4.-3}{8}=\dfrac{3}{2}\) 

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: \(\dfrac{-3}{6}=\dfrac{x}{-2}=\dfrac{-18}{y}=\dfrac{-z}{24}\)

=>\(\dfrac{x}{-2}=\dfrac{-18}{y}=\dfrac{z}{-24}=\dfrac{-1}{2}\)

=>\(\dfrac{x}{2}=\dfrac{18}{y}=\dfrac{z}{24}=\dfrac{1}{2}\)

=>\(x=2\cdot\dfrac{1}{2}=1;y=18\cdot\dfrac{2}{1}=36;z=\dfrac{24}{2}=12\)

\(-\frac{4}{8}=-\frac{1}{2}=\frac{5}{-10}=\frac{x}{-10}=-\frac{7}{14}=-\frac{7}{y}=\frac{12}{-24}=\frac{z}{-24}\)

=> x = 5; y = 14; z = 12.

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khó       ghê

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

Thanks