Toán Lớp 8: Tìm x biết `a)` `5(x-1)=0` `b)` `(x-3)^2 -25x^2=0`

U\omegaU        

 

a) 5(x-1)=0

      x-1  = 0 : 5

      x-1  = 0

      x      = 0+1

      x       = 1

b) (x-3)²-25x²=0

<=> (x-3-5x)(x-3+5x)=0

<=> (-4x-3)(6x-3)=0

<=> -3 (4x+3)(2x-1)=0

<=> \(\left[ \begin{array}{l}4x+3=0\\2x-1=0\end{array} \right.\) 

<=> \(\left[ \begin{array}{l}x=\frac{-3}{4} \\x=\frac{1}{2} \end{array} \right.\)

Vậy x =\frac{-3}{4} ;\frac{1}{2}