解方程:lg(8+2^x+1)=2x(1-lg5)

解方程:lg(8+2^x+1)=2x(1-lg5)


lg[8+2^(x+1)]=2x(1-lg5)lg[8+2^(x+1)]=2x(lg10-lg5)=2xlg2=lg[2^(2x)] 8 +2^(x+1)= 2^(2x)8 +(2^x)*2=[(2^x)]^2令a=2^x(a>0)8 + 2a =a^2 a^2 - 2a - 8=0(a-4)(a+2)=0 a=4或a=-2(舍去)所以a=2^x=4 x=2解…