Folosind formula [tex]a^{2} -b^{2} = (a-b)(a+b)[/tex] descompui expresia
[tex](x+\frac{a}{2}-(x-\frac{a}{2})) * (x+ \frac{a}{2}+x- \frac{a}{2)}[/tex]
[tex](x + \frac{a}{2}-x+ \frac{a}{2}) *2x[/tex]
(x-x se reduc, [tex]\frac{a}{2}+ \frac{a}{2} =a[/tex]
a*2x=2ax
