Помогите с алгеброй пожалуйста

X²+x-5=0
D=21
$x_{1} = \frac{-1- \sqrt{21} }{2} x_{2} = \frac{-1+ \sqrt{21} }{2}$
$x_{1} ^{2}* x_{2} ^{4}+ x_{2} ^{2} * x_{1} ^{4} = x_{1} ^{2} * x_{2} ^{2}*( x_{2} ^{2} + x_{1} ^{2} )$
$( \frac{-1- \sqrt{21} }{2}) ^{2} * ( \frac{-1+ \sqrt{21} }{2} )^{2} *(( \frac{-1- \sqrt{21} }{2} ) ^{2} +( \frac{-5+ \sqrt{21} }{2} ) ^{2} )$
= $( \frac{-1- \sqrt{21} }{2}* \frac{-1+ \sqrt{21} }{2} ) ^{2}*( \frac{1+2 \sqrt{21}+21+1-2 \sqrt{21} +21 }{4} ) = (\frac{21-1}{4} ) ^{2} *11=$
= $5^{2}*11=275$