[tex]\displaystyle\bf\\\frac{(-a^{3} )^{4} +(-a^{4} )^{3} +(-a^{2} )^{6}+(-a)^{12} }{(-a^{2} )^{4} +(-a^4)^{2} -(-a)^{8} } =\\\\\\=\frac{a^{12} -a^{12} +a^{12} +a^{12} }{a^{8}+a^{8} -a^{8} } =\frac{2a^{12} }{a^{8} } =2\cdot a^{12-8} =2a^{4} \\\\\\a=-\sqrt{2} \\\\\\2a^{4} =2\cdot(-\sqrt{2} )^{4} =2\cdot4=8\\\\\\Otvet \ : \ 8[/tex]