i keep getting stuck on these kind of questions, do i expand or try and factorise more???
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[tex]\bf \begin{array}{llll} (a^2+4)^2&-&(a^2-2)^2\\\\ a^4+8a^2+16&-&(a^4-2a^2+4)\\\\ a^4+8a^2+16&-&a^4+2a^2-4 \end{array} \\\\\\ a^4-a^4+8a^2+2a^2+16-4 \\\\\\ 10a^2+12[/tex]
expand, thus you can sum like-terms if any.