Odpowiedź:
[tex]20x(x+1)=(5+2x)^2\\\\20x^2+20x=25+20x+4x^2\\\\20x^2+20x-25-20x-4x^2=0\\\\16x^2-25=0\\\\(4x-5)(4x+5)=0\\\\4x-5=0\ \ \ \ \vee\ \ \ \ 4x+5=0\\\\4x=5\ \ /:4\ \ \vee\ \ \ \ 4x=-5\ \ /:4\\\\x=\frac{5}{4}\ \ \ \ \ \ \ \ \ \ \vee\ \ \ \ x=-\frac{5}{4}\\\\\\lub\\\\20x(x+1)=(5+2x)^2|\\\\20x^2+20x=25+20x+4x^2\\\\20x^2+20x-20x-4x^2=25\\\\16x^2=25\ \ /:16\\\\x^2=\sqrt{\frac{25}{16}}\\\\x=\sqrt{\frac{25}{16}}\ \ \ \ \vee\ \ \ \ x=-\sqrt{\frac{25}{16}}\\\\x=\frac{5}{4}\ \ \ \ \ \ \ \ \vee\ \ \ \ x=-\frac{5}{4}[/tex]
