Question

tìm x biết : a, \(x^2-5x=0\) 

b, \(\left(3x-5\right)^2-4=0\) 

c, 2018x - 1 + 2019x( 1-2018x )=0

d, \(\left(x+2\right)^3-x^2\left(x-6\right)=8\) 

e, ( 1 - 2x ) ( 1 + 2x ) - x( x+2 ) (x - 2 ) = 0 

 

Answer 1

x² - 5x = 0

=> x(x - 5) = 0

=> \(\orbr{\begin{cases}x=0\\x-5=0\end{cases}}\)

=> \(\orbr{\begin{cases}x=0\\x=5\end{cases}}\)

Answer 2

b)  (3x - 5)² - 4 = 0

=> (3x - 5)² = 0 + 4

=> (3x - 5)² = 4

=> (3x - 5)² = 2²

=> \(\orbr{\begin{cases}3x-5=2\\3x-5=-2\end{cases}}\)

=> \(\orbr{\begin{cases}3x=7\\3x=3\end{cases}}\)

=> \(\orbr{\begin{cases}x=\frac{7}{3}\\x=1\end{cases}}\)

Answer 3

b) ( 3x - 5 )² - 4 = 0

=> ( 3x - 5 )² = 4

=> ( 3x - 5 )² = 2²

=> 3x - 5 = 2

=> 3x = 7

=> x = 7/3