L\u00fd thuy\u1ebft \u0110\u1ecba L\u00ed 10 B\u00e0i 15: Th\u1ee7y quy\u1ec3n. M\u1ed9t s\u1ed1 nh\u00e2n t\u1ed1 \u1ea3nh h\u01b0\u1edfng \u0111\u1ebfn ch\u1ebf \u0111\u1ed9 n\u01b0\u1edbc s\u00f4ng. M\u1ed9t s\u1ed1 s\u00f4ng l\u1edbn tr\u00ean Tr\u00e1i \u0110\u1ea5t<\/a><\/blockquote>