Step-by-step explanation:
[tex]x {}^{4} - 8x {}^{2} + 16 \\ \\ by \: using \: middle \: term \: split \\ \\ x {}^{4} - 4x {}^{2} - 4x {}^{2} + 16 \\ \\ taking \: out \: common \\ \\ x {}^{2} (x { - 4)} - 4(x {}^{2} - 4) \\ \\ (x {}^{2} - 4)(x {}^{2} - 4)[/tex]