Sagot :
[tex]x^2-25=0\ \ \ \ | add\ 25\ to\ each\ side\\\\
x^2=25\ \ \ \ | \sqrt{}\\\\
x=\sqrt{25}\\\\
x=5\ or\ x=-5[/tex]
[tex]x^2-25=0\ \ \ \ \ \Leftrightarrow\ \ \ (x-5 )(x+5) =0 \ \ \Leftrightarrow\ \ \ x=5\ \ \ or\ \ \ x=-5[/tex]