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a) 5x³ - 5 = 0
5. ( x³ - 1 ) = 0
x³ - 1 = 0
x ³ = 1
x ³ = 1³
⇒ x = 1
Vậy x = 1
b) ( x + 1 )² - 6 = ( 3,5 )²
( x + 1 ) ² = 12.25 + 6
( x + 1 ) ² = 18.25
x + 1 = √18,25
x = √18,25 - 1
x ≈ 3.27
Vậy ...
c) ( 2x - 1 ) ³ : 5 = 25
( 2x - 1 ) ³ = 125
( 2x - 1 ) ³ = 5³
⇒ 2x - 1 = 5
2x = 6
x = 3
Vậy ...
d) $x^{17}$ = x
⇒ $x^{17}$ - x = 0
⇒ x.( $x^{16}$ - 1 ) = 0
⇒ \(\left[ \begin{array}{l}x=0\\x^{16}-1=0\end{array} \right.\)
⇒ \(\left[ \begin{array}{l}x=0\\x=1\end{array} \right.\)
Vậy...
e) 3x² - 6x = 0
3x ( x - 2 ) = 0
⇒\(\left[ \begin{array}{l}3x=0\\x-2=0\end{array} \right.\) ⇔ \(\left[ \begin{array}{l}x=0\\x=2\end{array} \right.\)
Vậy ...
i) 6x³ - 8 = 40
6x³ = 48
x³ = 8
x³ = 2²
⇒ x = 2
Vậy ...
