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,

\[x\text{ }=\text{ }\pm \text{ }3\text{ }or\text{ }x\text{ }=\text{ }\pm \text{ }1\]