25(x2-1)=0
x2-1=0:25
x2-1=0
x2=1
x=\(\sqrt{1}\)
25-25x2=0
⇔25(1-x2)=0
⇔25(1-x)(1+x)=0
⇔1-x=0 hay 1+x=0
⇔x=1 hay x=-1
\(\Rightarrow5^2-\left(5x\right)^2=0\)
\(\Leftrightarrow\left(5-5x\right)\left(5+5x\right)\)
\(\Leftrightarrow\left[{}\begin{matrix}5-5x=0\\5+5x=0\end{matrix}\right.\)
\(\Leftrightarrow\left[{}\begin{matrix}5x=5\\5x=-5\end{matrix}\right.\)
Vậy x = 1 hoặc x = -1
25 - 25x^2 = 0
25 . 1 - 25 . x^2 = 0
25 ( 1^2 - x^2 ) = 0
25 ( 1 + x ) ( 1 - x ) = 0
( 1 + x ) ( 1 - x ) = 25 : 0
( 1 + x ) ( 1 - x ) = 0
⇔ x = 0 - 1 hoặc x = 1 - 0
⇔ x = - 1 hoặc x = 1
Vậy x ∈ { 1 ; - 1 }