Cho h\u00e0m s\u1ed1 x\u00e1c \u0111\u1ecbnh v\u00e0 li\u00ean t\u1ee5c tr\u00ean kho\u1ea3ng (a;b) v\u00e0 x0<\/sub>\u00a0\u2208 (a; b)<\/p>\n \u2022 N\u1ebfu t\u1ed3n t\u1ea1i h > 0 sao cho f(x) < f(x0<\/sub>) v\u00e0 \u2200x \u2208(x0<\/sub>\u00a0– h; x0<\/sub>\u00a0+ h) v\u00e0 x \u2260 x0<\/sub>\u00a0th\u00ec ta n\u00f3i f \u0111\u1ea1t c\u1ef1c \u0111\u1ea1i t\u1ea1i x0<\/sub>.<\/p>\n \u2022 N\u1ebfu t\u1ed3n t\u1ea1i h > 0 sao cho f(x) > f(x0<\/sub>) v\u00e0 \u2200x \u2208(x0<\/sub>\u00a0– h; x0<\/sub>\u00a0+ h) v\u00e0 x \u2260 x0<\/sub>\u00a0th\u00ec ta n\u00f3i f \u0111\u1ea1t c\u1ef1c ti\u1ec3u t\u1ea1i x0<\/sub>.<\/p>\n Khi \u0111\u00f3:<\/p>\n + x0<\/sub>\u00a0l\u00e0 \u0111i\u1ec3m c\u1ef1c tr\u1ecb c\u1ee7a h\u00e0m s\u1ed1.<\/p>\n + f(x0<\/sub>) l\u00e0 gi\u00e1 tr\u1ecb c\u1ef1c tr\u1ecb c\u1ee7a h\u00e0m s\u1ed1.<\/p>\n + M(x0<\/sub>, f(x0<\/sub>)) l\u00e0 \u0111i\u1ec3m c\u1ef1c tr\u1ecb c\u1ee7a \u0111\u1ed3 th\u1ecb h\u00e0m s\u1ed1.<\/p>\n \u0110i\u1ec1u ki\u1ec7n c\u1ea7n v\u00e0 \u0111\u1ee7 \u0111\u1ec3 h\u00e0m s\u1ed1 \u0111\u1ea1t c\u1ef1c tr\u1ecb<\/p>\n \u0110i\u1ec1u ki\u1ec7n c\u1ea7n. N\u1ebfu h\u00e0m s\u1ed1 f(x) \u0111\u1ea1t c\u1ef1c tr\u1ecb t\u1ea1i x0<\/sub>\u00a0v\u00e0 h\u00e0m s\u1ed1 f(x) c\u00f3 \u0111\u1ea1o h\u00e0m t\u1ea1i \u0111i\u1ec3m x0<\/sub>\u00a0th\u00ec f'(x0<\/sub>)= 0 .<\/p>\n Ghi ch\u00fa: H\u00e0m s\u1ed1 f(x) c\u00f3 th\u1ec3 \u0111\u1ea1t c\u1ef1c tr\u1ecb t\u1ea1i m\u1ed9t \u0111i\u1ec3m m\u00e0 t\u1ea1i \u0111\u00f3 n\u00f3 kh\u00f4ng c\u00f3 \u0111\u1ea1o h\u00e0m.<\/p>\n \u0110i\u1ec1u ki\u1ec7n \u0111\u1ee7. Gi\u1ea3 s\u1eed h\u00e0m s\u1ed1 f(x) x\u00e1c \u0111\u1ecbnh tr\u00ean (a; b) v\u00e0 x0<\/sub>\u00a0\u2208 (a; b)<\/p>\n \u0110\u1ecbnh l\u00ed 1: N\u1ebfu f(x) c\u00f3 \u0111\u1ea1o h\u00e0m tr\u00ean (a; b)\\{x0<\/sub>} v\u00e0 v\u1edbi h > 0 sao cho (x0<\/sub>\u00a0– h; x0<\/sub>\u00a0+ h) \u2282 (a; b) ta c\u00f3<\/p>\n <\/p>\n => x0<\/sub>\u00a0l\u00e0 \u0111i\u1ec3m c\u1ef1c \u0111\u1ea1i c\u1ee7a h\u00e0m s\u1ed1.<\/p>\n <\/p>\n => x0<\/sub>\u00a0l\u00e0 \u0111i\u1ec3m c\u1ef1c ti\u1ec3u c\u1ee7a h\u00e0m s\u1ed1.<\/p>\n \u0110\u1ecbnh l\u00ed 2: Gi\u1ea3 s\u1eed h\u00e0m s\u1ed1 f(x) c\u00f3 \u0111\u1ea1o h\u00e0m c\u1ea5p hai tr\u00ean (a;b)<\/p>\n <\/p>\n => x0<\/sub>\u00a0l\u00e0 \u0111i\u1ec3m c\u1ef1c \u0111\u1ea1i c\u1ee7a h\u00e0m s\u1ed1.<\/p>\n <\/p>\n => x0<\/sub>\u00a0l\u00e0 \u0111i\u1ec3m c\u1ef1c ti\u1ec3u c\u1ee7a h\u00e0m s\u1ed1.<\/p>\n","protected":false},"excerpt":{"rendered":" Cho h\u00e0m s\u1ed1 x\u00e1c \u0111\u1ecbnh v\u00e0 li\u00ean t\u1ee5c tr\u00ean kho\u1ea3ng (a;b) v\u00e0 x0\u00a0\u2208 (a; b) \u2022 N\u1ebfu t\u1ed3n t\u1ea1i h > 0 sao cho f(x) < f(x0) v\u00e0 \u2200x \u2208(x0\u00a0– h; x0\u00a0+ h) v\u00e0 x \u2260 x0\u00a0th\u00ec ta n\u00f3i f \u0111\u1ea1t c\u1ef1c \u0111\u1ea1i t\u1ea1i x0. \u2022 N\u1ebfu t\u1ed3n t\u1ea1i h > 0 sao cho f(x) […]<\/p>\n","protected":false},"author":3,"featured_media":28078,"comment_status":"closed","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"_mi_skip_tracking":false,"tdm_status":"","tdm_grid_status":""},"categories":[157],"tags":[1447,1446],"yoast_head":"\n