Logarit(1) Bµi I. TÝnh: 10 3 3 1 2 2 10 3 1 1) log ; 100 2)log 3 3)log 4 1 4) log 2 1 5) log 10 3 0,5 log 12 log 1 1 5 6)9 7)0,125 8) log 125 0,5 1 4 1 9)log 2 1 10) log 64 3 3 2 2 1 6 log 18 5log 2 log 5 log 5 11) log 36 12)3 13)3 1 14)( ) 8 1 15) 32    ÷   Bµi II.TÝnh: ( ) 7 7 7 1 3 2 4 5 5 5 3 7 7 7 log 16 1) log 15 log 30 2) log log 4.log 3 1 3) log 3 log 12 log 50 2 1 4) log 36 log 14 3log 21 2 − − + − − 8 8 8 5 5 5 5) log 12 log 15 log 20 log 36 log 12 6) log 9 − + − 6 2 log 5 log 3 1 log 2 7)36 10 8 4 1 3 9 8) log log 36 log 9 2 2 2 − + − + + 1 1 9) lg lg 4 4 lg 2 8 2 1 10) lg lg 0,375 2 lg 0,5625 8 27 11)lg 72 2 lg lg 108 256 + + − + − + 12) 3 81 2log 4 4log 2 9 + Bµi III. T×m x, biÕt: ( ) 3 3 3 3 3 9 1) log 1 2 2) log 4 log 7 log 3 3)log log 2 x x a b x x − = = + + = 5 5 5 4) log 2 log 3log 5) log 27 3 x x a b = − = 1 7)log 1 7 8) log 5 4 x x = − = − Bµi IV. Kh«ng dïng m¸y tÝnh, h·y so s¸nh: 1) lg 2 lg3 + vµ lg5 3)lg12-lg5 vµ lg7 2)3log2+lg3 vµ 2lg5 4) 1+2lg3 vµ lg27 Bµi V. BiÓu diÔn logarit sau qua a vµ b: 1) 3 3 3 log 50; log 15; log 10a b = = 2) 4 2 log 1250; log 5a = Logarit(2) Bµi I. TÝnh: 7 5 4 6 6 3 2 2 1 5 5 log 3 log 2 1 log log 2 3 3 3 4 2 1 2 2 log 4 log 8 log 2 log 3 2 7 3 5 1)49 25 2)36 3)log 4 log 2 log 2 4)4 .8 5)25 6) log 5.log 2.log 7.log 3 + + − + − 3 9 6 log 4 log 36 log 5 7)36 3 3 + − 2 3 3 log 3 2 log 2 log 4 3 .4 8) 27 − 4 1 3 3 5 3 4 1 3 3 3 4 5 6 7 8 3 4 6 3 3 15 3 .5 27 log 27 log 9 9) 1 1 log log 81 3 log 2.log 3.log 4.log 5.log 6.log 7 10) log 6.log 9.log 2 log 135 log 5 11) log 3 log 3   +  ÷     +  ÷   − Bµi II.1) Cho 12 log 27 .= m tÝnh log 6 16 theo m. 2) Cho log 2 3=a; log 5 2=b. TÝnh log 12 5 vµ 2 10 log 30 theo a vµ b? 3) Cho log 30 3=a; log 30 5=b; TÝnh log 30 2 theo a vµ b. 4)Cho a=log 2 3; b=log 3 5; 3 7 log 2 = c . tÝnh log 140 63? 5) Cho log 3 15=a; log 3 10=b. tÝnh 3 log 50 theo a vµ b. Bµi III. Chøng minh: ( ) . log log 1) log 1 log + = + a a a x a b x bx x 2 1 1 1 ( 1) 2) . log log log 2log + + + + = k a a a a k k x x x x 3) NÕu ( ) 2 2 2 ; ; 0; 1 + = > ± ≠ a b c a b c c b th× log log 2log .log + − + − + = b c c b b c c b a a a a 4) NÕu log x a; log y b; log z c t¹o thµnh mét cÊp sè céng th× 2log .log log log log = + a c b a c x z y x z 5) lg(x+2y)-2lg2= 1 2 (lgx+lgy) víi x,y > 0; 2 2 4 12+ =x y xy 6) Cho a=log 12 18; b=log 24 54. C/m: ab+5(a-b)=0. . 1+2lg3 vµ lg27 Bµi V. BiÓu diÔn logarit sau qua a vµ b: 1) 3 3 3 log 50; log 15; log 10a b = = 2) 4 2 log 1250; log 5a = Logarit( 2) Bµi I. TÝnh: 7 5 4 6. Logarit( 1) Bµi I. TÝnh: 10 3 3 1 2 2 10 3 1 1) log ; 100 2)log 3 3)log 4 1 4)