335. La expresión ${{\left( x-a \right)}^{2}}-{{\left( x+a \right)}^{2}}$ es igual a

a) 0

b) $-4ax$

c) $-2{{a}^{2}}$

Operando:

${{\left( x-a \right)}^{2}}-{{\left( x+a \right)}^{2}}\ \ =\ \ \left( {{x}^{2}}-2xa+{{a}^{2}} \right)-\left( {{x}^{2}}+2xa+{{a}^{2}} \right)\ \ =$

$=\ \ {{x}^{2}}-2xa+{{a}^{2}}-{{x}^{2}}-2xa-{{a}^{2}}\ \ =\ \ -4xa\ \ =\ \ -4ax$