Question

解 指数方程和对数方程 求详细解题思路 与步骤 谢谢

求详细解题思路 与步骤 谢谢

Answer 1

(1) e^x=18 x=ln 18=2.8903717578961646922077225953032......
(2) x/2=8 x=8X2=16
(3) lg(x-1)+lg(x+2)=1 (x-1)(x+2)=10 x^2+x-2=10 x^2+x-12=0 (x-3)(x+4)=0 x1=3 x2=-4(舍去)
(4) 2lg x-lg 3x = lg 5 lg x^2 - lg 3x = lg 5 x^2/(3x)=5 x/3=5 x=15

Answer 2

1）x=ln18
2)2^(-x)=2^3 -x=3 x=-3
3)lg(x-1)(x+2)=1 (x-1)(x+2)=10 x^2+x-12=0 x=3,-4 所以x=3
4) 2lgx-(lg3+lgx)=lg5 lgx=lg3+lg5 lgx=lg15 x=15

Answer 3

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