Ki\u1ebfn th\u1ee9c \u00e1p d\u1ee5ng<\/strong><\/p>\n\n\n\nKhi s\u1eed d\u1ee5ng c\u00e1c ph\u00e9p bi\u1ebfn \u0111\u1ed5i t\u01b0\u01a1ng \u0111\u01b0\u01a1ng ta nh\u1eadn \u0111\u01b0\u1ee3c c\u00e1c BPT t\u01b0\u01a1ng \u0111\u01b0\u01a1ng. <\/p>\n\n\n\n
C\u00e1c ph\u00e9p bi\u1ebfn \u0111\u1ed5i t\u01b0\u01a1ng \u0111\u01b0\u01a1ng g\u1ed3m: <\/p>\n\n\n\n
+ C\u1ed9ng ho\u1eb7c tr\u1eeb hai v\u1ebf c\u1ee7a BPT v\u1edbi c\u00f9ng m\u1ed9t bi\u1ec3u th\u1ee9c: <\/p>\n\n\n\n
P(x) < Q(x) \u21d4 P(x) + f(x) < Q(x) + f(x).<\/p>\n\n\n\n
+ Nh\u00e2n ho\u1eb7c chia hai v\u1ebf c\u1ee7a BPT v\u1edbi c\u00f9ng m\u1ed9t bi\u1ec3u th\u1ee9c kh\u00e1c 0. <\/p>\n\n\n\n
P (x) < Q(x) \u21d4 P(x).f(x) < Q(x).f(x) n\u1ebfu f(x) > 0<\/p>\n\n\n\n
P(x) < Q(x) \u21d4 P(x).f(x) > Q(x).f(x) n\u1ebfu f(x) < 0.<\/p>\n\n\n\n
+ N\u00e2ng l\u00ean l\u0169y th\u1eeba b\u1eadc ch\u1eb5n c\u1ee7a BPT c\u00f3 c\u1ea3 hai v\u1ebf \u0111\u1ec1u d\u01b0\u01a1ng: <\/p>\n\n\n\n
0 < P(x) < Q(x) \u21d4 P2n<\/sup>(x) < Q2n<\/sup>(x)<\/p>\n\n\n\n+ N\u00e2ng l\u00ean l\u0169y th\u1eeba b\u1eadc l\u1ebb c\u1ea3 hai v\u1ebf c\u1ee7a BPT <\/p>\n\n\n\n
P(x) < Q(x) \u21d4 P2n+1<\/sup>(x) < Q2n+1<\/sup>(x).<\/p>\n\n\n\n+ Khai c\u0103n b\u1eadc hai c\u1ee7a BPT c\u00f3 c\u1ea3 hai v\u1ebf \u0111\u1ec1u d\u01b0\u01a1ng : <\/p>\n\n\n\n
0 < P(x) < Q(x) \u21d4 \u221aP(x) < \u221aQ(x)<\/p>\n\n\n\n
+ Khai c\u0103n b\u1eadc ba c\u1ea3 hai v\u1ebf c\u1ee7a BPT : <\/p>\n\n\n\n