+14997 Factor completely: x^8 - 12x^4 - 64.
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\(x^8 - 12x^4 - 64 \)
\(u=x^4\)
\(u^2-12u-64=0\)
p q
\(u=-\frac{p}{2}\pm\sqrt{(\frac{p}{2})^2-q}\\ u=6\pm\sqrt{36+64}\\ u=6\pm 10\)
\(u_{1,2}=16\\ u_{3,4}=-4 \)
\(u=x^4\)
\(x^8 - 12x^4 - 64 \)
\(=(x^4-16)(x^4+4)\\ =(x^2+4)(x+2)(x-2)(x^4+4)\)
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