81k^4+12k^2+108k+32=0

假设方程形如:(9k＾2加b)＾2加c(y＾2加d)＾2=0待定系数:18b加c=12，2cd=108，cd＾2=32自己解

>> solve('81*k^4+12*k^2+108*k+32=0')

ans =

[ 1/18*2^(1/2)*((-4*(53873+9*27757137^(1/2))^(1/3)+(53873+9*27757137^(1/2))^(2/3)+868)/(53873+9*27757137^(1/2))^(1/3))^(1/2)+1/18*i*((16*(53873+9*27757137^(1/2))^(1/3)*((-4*(53873+9*27757137^(1/2))^(1/3)+(53873+9*27757137^(1/2))^(2/3)+868)/(53873+9*27757137^(1/2))^(1/3))^(1/2)+2*((-4*(53873+9*27757137^(1/2))^(1/3)+(53873+9*27757137^(1/2))^(2/3)+868)/(53873+9*27757137^(1/2))^(1/3))^(1/2)*(53873+9*27757137^(1/2))^(2/3)+1736*((-4*(53873+9*27757137^(1/2))^(1/3)+(53873+9*27757137^(1/2))^(2/3)+868)/(53873+9*27757137^(1/2))^(1/3))^(1/2)+972*2^(1/2)*(53873+9*27757137^(1/2))^(1/3))/(53873+9*27757137^(1/2))^(1/3)/((-4*(53873+9*27757137^(1/2))^(1/3)+(53873+9*27757137^(1/2))^(2/3)+868)/(53873+9*27757137^(1/2))^(1/3))^(1/2))^(1/2)]
[ 1/18*2^(1/2)*((-4*(53873+9*27757137^(1/2))^(1/3)+(53873+9*27757137^(1/2))^(2/3)+868)/(53873+9*27757137^(1/2))^(