y=log1/2 (x+根号下(x^2-2)),(y =< -1/2 )对两边求 (1/2)^ 且x,y互换得
(1/2)^x = y + (y2 -2)^(1/2) y移向 ,平方得
y = 2^x + 1/2 * (1/2)^x