a)
[tex]25x^2-121=0\\\\(5x-11)(5x+11)=0\\\\5x-11=0\ \vee\ 5x+11=0\\\\5x=11\ /\ :\ 5\ \vee\ 5x=-11\ /\ :\ 5\\\\x=\frac{11}{5}\ \vee\ x=-\frac{11}5\\\\x=2\frac15\ \vee\ x=-2\frac15[/tex]
b)
[tex]0,01-0,04x^2=0\ /\ \cdot\ 100\\\\1-4x^2=0\\\\(1-2x)(1+2x)=0\\\\1-2x=0\ \vee\ 1+2x=0\\\\-2x=-1\ /\ :\ (-2)\ \vee\ 2x=-1\ /\ :\ 2\\\\x=\frac12\ \vee\ x=-\frac12[/tex]
c)
[tex]25x^2-225=0\ /\ :\ 25\\\\x^2-9=0\\\\(x-3)(x+3)=0\\\\x-3=0\ \vee\ x+3=0\\\\x=3\ \vee\ x= -3[/tex]
