Question

Tìm x \(\in\) Z biết:

a) x² = 16

b) x³ = -8

Answer 1

a) x² = 16

x² = 4² = (-4)²

=> \(x\in\left\{4;-4\right\}\)

Vậy \(x\in\left\{4;-4\right\}\)

b) x³ = -8

x³ = (-2)³

=> x = -2

Vậy x = -2

Answer 2

a )

\(x^2=16\)

\(x^2=4^2\)

\(\Rightarrow x=4\).

b ) 

\(x^3=-8\)

\(x^3=\left(-2\right)^3\)

\(\Rightarrow x=\left(-2\right)\).

Answer 3

a) =>  x = \(\sqrt{16}\) = 4           hoặc               x = -\(\sqrt{16}\) = -4

b) => x = \(\sqrt[3]{-8}\) = -2

Answer 4

a) x= 4 và -4

b) x = -2

Answer 5

a/

=> x² = (+-4)²

=>x = 4 hoặc -4

b/ 

=> x³ = (-2)³ => x = -2

Answer 6

\(a\)) \(x^2=16\)

\(\Rightarrow x^2=\left(-4,4\right)^2\)

\(\Rightarrow\orbr{\begin{cases}x=-4\\x=4\end{cases}}\)

Vậy \(x\in\left\{-4,4\right\}\)

\(b\)) \(x^3=-8\)

\(\Rightarrow x^3=\left(-2\right)^3\)

\(\Rightarrow x=-2\)

Vậy \(x=-2\)