I know a regular language is the one which can be expressed as a regular expression or we can create a DFA corresponding to it. Unless a language has a pattern in which one part has to match with other like in $$a^nb^n|n\geq 0 (CFG)$$ It'll be regular. Like AP Series of symbols can be easily expressed as Regular expression but GP Series can not.
But I failed to understand why the following languages are regular
$L_1=\{wxw^R \mid w,x \in (a,b)^+\}$
$L_2=\{wxwy \mid w,x,y \in (a,b)^+\}$
$L_3=\{xwyw \mid w,x,y \in (a,b)^+\}$