5x^2 - 10 = 0
5x^2 = 10
x^2 = 10/5
x^2 = 2
\|(1+2\|2)^2 - \|( 1 - 2\|2)^2+2,5= 1+ 2\|2 - 2\|2 +1+2,5=2+2,5=4,5