[tex]a=1\\\sqrt{1+1x} =\sqrt{1-1x} +x\\\sqrt{1+x} =\sqrt{1-x} +x\\1+x=1-x+2x\sqrt{1-x} +x^2\\x=-x+2x\sqrt{1-x} +x^2\\-2x\sqrt{1-x} =-x+x^2-x\\-2x\sqrt{1-x} =-2x+x^2\\4x^2(1-x)=x^4-4x^3+4x^2\\4x^2-4x^3=x^4-4x^3+4x^2\\0-4x^3=x^4-4x^3\\0=x^4\\x^4=0\\x=0[/tex]
La fel si daca a va fi -1 rezultatul va da tot 0.
