a) $\sqrt{1+x}-\sqrt{1-x}-x=0$
b) $\sqrt{4x+1}-\sqrt{3x-2} - \frac{x+3}{5}=0$
c) $\sqrt{x^{2}+4x+7}+\sqrt{x^{2}+6x+14}+\sqrt{x+2}-6=0$
d) $\sqrt{3x+1}-\sqrt{6-x}+3x^{2}-14x-8=0$
e) $\left | x-2012 \right |^{3}+\left | 2013-x \right |^{4}-1=0$
f) $\sqrt{x+2015^{2}}+\sqrt{x+2012^{2}}-\sqrt{x+2014^{2}}-\sqrt{x+2013_{2}}=0$