Răspuns :
[tex] (x-1)^{2} = x^{2}-2x+1[/tex]
[tex](x+1)^{2} = x^{2} +2x+1 [/tex]
[tex] x^{2} +2x+1-( x^{2} -2x+1)= x^{2}+2x+1- x^{2} +2x-1 = 4x[/tex]
[tex](x+1)^{2} = x^{2} +2x+1 [/tex]
[tex] x^{2} +2x+1-( x^{2} -2x+1)= x^{2}+2x+1- x^{2} +2x-1 = 4x[/tex]