Given condition, \[x4\text{ }\text{ }10×2\text{ }+\text{ }9\text{ }=\text{ }0\]
\[x4\text{ }\text{ }x2\text{ }\text{ }9×2+\text{ }9\text{ }=\text{ }0\]
\[x2\left( x2\text{ }\text{ }1 \right)\text{ }\text{ }9\left( x2\text{ }\text{ }1 \right)\text{ }=\text{ }0\]
\[\left( x2\text{ }\text{ }9 \right)\left( x2\text{ }\text{ }1 \right)\text{ }=\text{ }0\]
In this way, we have
\[x2\text{ }\text{ }9\text{ }=\text{ }0\text{ }or\text{ }x2\text{ }\text{ }1\text{ }=\text{ }0\]
Thus,
\[x\text{ }=\text{ }\pm \text{ }3\text{ }or\text{ }x\text{ }=\text{ }\pm \text{ }1\]