Solution:
Solution
The given equation can be written as
$$(7-x-1)^{4}+(7-x+1)^{4}=16$$<br>
or $$(t-1)^{4}+(t+1)^{4}=16$$ where $$t=7-x$$<br>
or $$t^{4}+6t^{2}-7=0$$ or $$(t^{2}-1)(t^{2}+7)=0$$<br>
$$t^{2}=(7-x)^{2}=1,-7$$<br>
or $$7-x=1,-1\pm i\sqrt{7}1$$<br>
$$x=6,8,7+i\sqrt{7},7-i\sqrt{7}$$
