C\u00e2u 15:<\/b>\u00a0N\u1ebfu a = log8<\/sub>225 v\u00e0 b = log2<\/sub>15 th\u00ec gi\u1eefa a v\u00e0 b c\u00f3 h\u1ec7 th\u1ee9c<\/p>\n <\/p>\n C\u00e2u 16:<\/b>\u00a0Kh\u1ed1i l\u01b0\u1ee3ng m c\u1ee7a m\u1ed9t ch\u1ea5t ph\u00f3ng x\u1ea1 thay \u0111\u1ed5i theo th\u1eddi gian t tu\u00e2n theo c\u00f4ng th\u1ee9c<\/p>\n <\/p>\n trong \u0111\u00f3 m0<\/sub>\u00a0l\u00e0 kh\u1ed1i l\u01b0\u1ee3ng ch\u1ea5t ph\u00f3ng x\u1ea1 ban \u0111\u1ea7u, T l\u00e0 chu k\u00ec b\u00e1n r\u00e3. N\u1ebfu vi\u1ebft ph\u01b0\u01a1ng tr\u00ecnh n\u00e0y d\u01b0\u1edbi d\u1ea1ng m = m0<\/sub>e-kt<\/sup>th\u00ec :<\/p>\n <\/p>\n C\u00e2u 17:<\/b>\u00a0\u0110\u1eb7t log8<\/sub>3 = p v\u00e0 logn<\/sub>x = 3logm<\/sub>x . H\u00e3y bi\u1ec3u th\u1ecb log5 theo p v\u00e0 q<\/p>\n <\/p>\n C\u00e2u 18:<\/b>\u00a0Cho m, n > 1 v\u00e0 logn<\/sub>x = 3logm<\/sub>x v\u1edbi m\u1ecdi x > 0. H\u00e3y bi\u1ec3u th\u1ecb m theo n<\/p>\n A. m = n3<\/sup>\u00a0\u00a0\u00a0\u00a0B. m = 1\/n3<\/sup>\u00a0\u00a0\u00a0C. m = \u221bn \u00a0\u00a0\u00a0D. m = 1\/\u221bn<\/p>\n C\u00e2u 19:<\/b>\u00a0Bi\u1ebft r\u1eb1ng 4a<\/sup>\u00a0= 5, 5b<\/sup>\u00a0= 6, 6c<\/sup>\u00a0= 7, 7d<\/sup>\u00a0= 8. T\u00ednh abcd<\/p>\n A. 1\/2 \u00a0\u00a0\u00a0B. 3\/2 \u00a0\u00a0\u00a0C. 2\u00a0\u00a0\u00a0D. 2\/3<\/p>\n C\u00e2u 20:<\/b>\u00a0Cho b > 1, sinx > 0, cosx > 0 v\u00e0 logb<\/sub>sinx = a. Khi \u0111\u00f3 logb<\/sub>cosx b\u1eb1ng<\/p>\n <\/p>\n H\u01b0\u1edbng d\u1eabn gi\u1ea3i v\u00e0 \u0110\u00e1p \u00e1n<\/b><\/p>\n C\u00e2u 15:<\/b><\/p>\n a = log8<\/sub>225 = log23<\/sup><\/sub>152<\/sup>\u00a0= (2\/3)log2<\/sub>15 = 2b\/3<\/p>\n C\u00e2u 16:<\/b><\/p>\n <\/p>\n <\/p>\n C\u00e2u 17:<\/b><\/p>\n <\/p>\n C\u00e2u 18:<\/b><\/p>\n <\/p>\n => logx<\/sub>m = 3logx<\/sub>n = logx<\/sub>n3<\/sup>\u00a0=> m = n3<\/sup><\/p>\n C\u00e2u 19:<\/b><\/p>\n T\u1eeb gi\u1ea3 thi\u1ebft ta c\u00f3: a = log4<\/sub>5, b = log5<\/sub>6, c = log6<\/sub>7, d = log7<\/sub>8<\/p>\n => abcd = log4<\/sub>5.log5<\/sub>6.log6<\/sub>7.log7<\/sub>8 = log4<\/sub>6log6<\/sub>7log7<\/sub>8 = log4<\/sub>7.log7<\/sub>8 = log4<\/sub>8 = log22<\/sup><\/sub>23<\/sup>\u00a0= (3\/2)log2<\/sub>2 = 3\/2<\/p>\n C\u00e2u 20:<\/b><\/p>\n logb<\/sub>sinx = a => sin x = ba<\/sup>\u00a0=> sin2<\/sup>x = b2a<\/sup>\u00a0=> cosx = (1 – b2a<\/sup>)1\/2)<\/sup><\/p>\n => logb<\/sub>cosx = (1\/2)logb<\/sub>(1 – b2a<\/sup>)<\/p>\n","protected":false},"excerpt":{"rendered":" C\u00e2u 15:\u00a0N\u1ebfu a = log8225 v\u00e0 b = log215 th\u00ec gi\u1eefa a v\u00e0 b c\u00f3 h\u1ec7 th\u1ee9c C\u00e2u 16:\u00a0Kh\u1ed1i l\u01b0\u1ee3ng m c\u1ee7a m\u1ed9t ch\u1ea5t ph\u00f3ng x\u1ea1 thay \u0111\u1ed5i theo th\u1eddi gian t tu\u00e2n theo c\u00f4ng th\u1ee9c trong \u0111\u00f3 m0\u00a0l\u00e0 kh\u1ed1i l\u01b0\u1ee3ng ch\u1ea5t ph\u00f3ng x\u1ea1 ban \u0111\u1ea7u, T l\u00e0 chu k\u00ec b\u00e1n r\u00e3. N\u1ebfu vi\u1ebft ph\u01b0\u01a1ng […]<\/p>\n","protected":false},"author":3,"featured_media":27509,"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\n\n
\n 15-A<\/td>\n 16-C<\/td>\n 17-C<\/td>\n 18-A<\/td>\n 19-B<\/td>\n 20-D<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n