log7 3倍的根號4, 這個應(yīng)該是4的開立方
原式=log(5,2)log(7,3)/[-log(5,3)log(7,4)/3]+log(2,[根號(3+根號5)—根(3-根號5)])
=-3log(3,2)log(4,3)+log(2,[根號(3+根號5)—根(3-根號5)]^2)/2
=-3log(3,2)/log(3,4)+log(2,{(3+根號5)+(3-根號5)-2根號[(3+根號5)(3-根號5)]})/2
=-3log(4,2)+log(2,2)/2
=-3/2+1/2
=-1