We have
$x^2-2x + 2 \equiv 0 \pmod 5$
$=>x^2 -2x + 1 + 1 \equiv 0 \pmod 5$ to make square on left side
$=>(x-1)^2 + 1 \equiv 0 \pmod 5$
$=>(x-1)^2 + 1 \equiv 0 \pmod 5$
$=>(x-1)^2 \equiv 4 \pmod 5$
Working in mod 5 we have
$0^2 \equiv 0 \pmod 5$
$1^2 \equiv 1 \pmod 5$
$2^2 \equiv 4 \pmod 5$
$3 \equiv 4 \pmod 5$
$4^2 \equiv 1 \pmod 5$
So we have
$x-1 \equiv 2\pmod 5$ or $x-1 \equiv 3 \pmod 5$
Or $ x \equiv 3 \pmod 5 $ or $x \equiv 4 \pmod 5$
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