[tex](1 \frac{1}{5} )^{2}- ( \frac{7}{10} )^{2}+ (1 \frac{1}{5}- \frac{7}{10} )^{2} =[/tex]
[tex]=(1 \frac{1}{5} )^{2}- ( \frac{7}{10} )^{2}+(1 \frac{1}{5} )^{2} -2*1 \frac{1}{5} *\frac{7}{10}+( \frac{7}{10} )^{2}=[/tex]
[tex]=2* (1 \frac{1}{5} )^{2} -2*(1 \frac{1}{5} )* \frac{7}{10}= [/tex]
[tex]=2* ( \frac{6}{5} )^{2} -2* \frac{6}{5}* \frac{7}{10} =[/tex]
[tex]=2* \frac{36}{25} -2* \frac{42}{50} =[/tex]
[tex]= \frac{72}{25} -\frac{84}{50} = \frac{144-84}{50}= \frac{60}{50} = \frac{6}{5} [/tex]
