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对数与对数运算练习题及答案选择题1. 2 3=1化为对数式为() 8A. log-2=-3 8C. log 21-= - 3 82. log63+log62 等于()A. 6B. 53. 如果 lgx=lga+21gb 3lgc,A. a+2b3cB. log”3) = 281D. 1og2(-3)=-8C. 1D. log65则x等于()8. a+b2 c3C.ab2c3D.2ab3c4.已知 a=1og32,那么 1og3821og36 用 a 表示为()A . a 2C. 3a(1 +a)2q 卜二5.B. 5a2D. 3a a2T的值等于(A. 2+V5B.5c. 2+26. Log2.2的值为(A. - V2D.51+2C.B. .2D.27.在b=1og(a-2)(5a)中,实数a的取值范围是()A . a 5 或 a2C. 2a/3B. 2vav 3或 3vav5D. 3a0 且w1),贝U 1ogx(abc)=(4277A.7B.7C.2D.二.填空题1 .210g510+ 1og50.25=.2 .方程 1og3(2x 1) = 1 的解为 x=.3 .若 1g(1nx)=0,则 x=.4 .方程9x6 3x 7=0的解是5 .若 log34 10g48 10g8m = log416,则 m =.6 .已知 loga2= m, log a3 = n,则 loga18 =.(用 m, n 表示)7 . log6log 4(log381) =.8 .使对数式10g(x-1乂3x)有意义的x的取值范围是 三.计算题1 .计算:(1)210g210 +log20.04lg3 + 21g2 1(2)1g1.210g 6:1 21og 63+ 110g627123(4)1og 2(V3+2)+1og2(2-V3);2.已知 10g34 10g48 log8m= 1og416,求 m 的值.对数与对数运算练习题答案一.选择题1. C 2. C 3. C 4. A 5. B 6. D 7. B 8 A 9. A 10.B11.B12.D二.填空题1.22.23. e4. x= log375.96. m+2n 7.08. 1x3 且 xw 2三.计算题1 .解:(1)2log2l0+log20.04= log2(100X 0.04)= log24= 2(2)lg3 + 2lg2 1 lg(3X4+10) 12 = 1lg1.2lg1.2lg1.2(3)log6:1 2log63+1log627= log6:1- 10g69+log63 12312=10g64X 1-X 3)= 10g 6 = - 2.12 936(4)log2(3+2)+log2(2-V3)=10g2(2 + 3)(2 小)=10g21 = 0.2 .解析10g416= 2, 2g3410g4810g8m= log3m = 2, m= 9.3 4
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