FX = ax ^ 2 + LNX if FX1 = (A-1 / 2) x ^ 2 + 2aX + (1-A ^ 2) LNX, FX2 = 1 / 2x ^ 2 + 2aX On (1, positive infinity), FX has FX1 in the common domain

FX = ax ^ 2 + LNX if FX1 = (A-1 / 2) x ^ 2 + 2aX + (1-A ^ 2) LNX, FX2 = 1 / 2x ^ 2 + 2aX On (1, positive infinity), FX has FX1 in the common domain

Ax ^ 2 + LNX - (A-1 / 2) x ^ 2-2ax - (1-A ^ 2) lnx0, i.e
1/2x^2-2ax+a^2lnx>0
(1/2-a)x^2+2ax-lnx>0
To be true on (1, positive infinity), we must:
1/2-a>0 2a0 a/(1/2-a)0
The solution is: - 1 / 2