Obliczenia :
[tex]x^2=(5\sqrt7)^2+(2\sqrt7)^2\\\\x^2=5^2\cdot(\sqrt7)^2+2^2\cdot(\sqrt7)^2\\\\x^2=25\cdot7+4\cdot7\\\\x^2=175+28\\\\x^2=203\\\\\underline{x=\sqrt{203}}[/tex]
