Bài 4 Giải hệ phương trình.[r]
(1)Chuyên đề PT, BPT Mũ – Lôgarit http://toanhocmuonmau.violet.vn LuyÖn TËp Ph−¬ng Tr×nh, HÖ Ph−¬ng Tr×nh L«garit Bài 1Giải phương trình: 22) log x + log 16 x − = 23) log (3x − 1) log (3x +1 − 3) = + =1 − lg x + lg x 2) log 16 + log2x 64 = x 1) 24) log log x + log log x = log 0,04 x + + log 0,2 x + = 3) 25) log x + log x = log 4) log x + 10 log x + = 26) 5) 3log x 16 − log16 x = log x ( ) ( ( 7) lg 6.5 + 25.20 x ( 8) x + lg − x x x ) ) = x + lg 25 + =1 − lg x + lg x ( ) = x lg + lg3 ) 30) log5 x + log25 x = log 0,2 lg x 31) lg(x + 2x − 3) + lg 32) log ( x +3 ) 12) =x 13) log log x + log log x = 14) log x + log x = log x + log x+3 =0 x −1 lg(5x − 4) + lg x + = + lg 0,18 33) 3log x 16 − log16 x = log x x + 34) lg(lg x) + lg(lg x − 2) = ( ) ( ) 15) log x (125x) log 25 x = 35) log 4.3 − − log − = 17) log 22 x + log 36) log3 log9 x + 16) (x − 1) log [4( x −1) ] = (x − 1) 18) 2.2 ( x− ) x x + x = 2x x x 37) lg 6.5 + 25.20 = x + lg25 x −2=0 ( = log ( 2x ) 19) x = x 3log2 x − x log2 20) + log ( x − 1) = log x −1 log 38) log32 x ) + x log3 x = 162 21) lg x − lg x = lg x − 39) log (x − x − 1) log (x + x − 1) = log x − x − log (3x − 1) log (3x +1 − 3) = ( 40) log2 x +1 ( ) + log x + = log 41) ( x + ) log3 42) log (sin ) 2 ( x + 1) + ( x + 1) log3 ( x + 1) − 16 = x x − sin x) + log (sin + cos 2x) = (Đề 3) 2 43) log (x − x − 1) log (x + x − 1) = log x − x − Gi¸o viªn: Th©n V¨n Dù 29) log x 2x − 5x + = = 50 − x lg5 log x log x 10) 3 + x = 162 11) log3 ( x + 1) + log5 ( 2x + 1) = 9) + log x + 27) log ( x + 3) = x 28) log5 x = log5 ( x + ) − log5 ( x + ) 6) log 4.3 − − log − = x x §T: 0984 214 648 (2) Chuyên đề PT, BPT Mũ – Lôgarit http://toanhocmuonmau.violet.vn Bài Cho phương trình: (m – 3) log 21 (x − 4) – (2m + 1) log (x − 4) + m + = 2 tìm m để phương trình có nghiệm x1, x thoả mãn < x1 Bài Giải các hệ phương trình sau: x − + − y = 5) 1) 3log (9x ) − log y = x−2 y x− y 6) ( ) = ( ) 2) log ( x − y ) + log ( x − y ) = 7) log ( y − x) − log y = 3) x + y = 25 8) 4−x ( x + − 1)3y = 4) x y + log x = < x2 < x log8 y + y log8 x = log x − log y = x − y + = log x − log2 y = log ( x + y ) = 2 log x + log y = log x y + log y x = x − x − y = 20 + log y x Bài Giải hệ phương trình lg x + lg y = 1) 2 x + y = 29 lg x + y = + 3lg2 2) lg ( x + y ) − lg ( x − y ) = lg3 log x − log y = 3) 2 x − 5y + = ( ) Gi¸o viªn: Th©n V¨n Dù x+y y x = 32 4) log3 ( x + y ) = − log3 ( x + y ) log x xy = log y x 5) log x y y = 4y + 3 − x y = 1152 6) log ( x + y ) = §T: 0984 214 648 (3)