Question

若只有一个x值满足方程(1-lga*lga)x^2+(1-lga)x+2=0,求实数a的值

Answer 1

(1)1-lga*lga=0时,lga=-1满足题意,a=0.1;

(2)1-lga*lga=/0时,根据一元二次方程性质,(1-lga)^2-4*2*(1-lga*lga)=0;

lga=-7/9,a=10^(-7/9);