求大神帮助指点，该怎么才能逆变换成功呢
ilaplace((10000000000*(22090000000000*s^3 + 47000000000*s^2 + 23525002209*s + 25000000))/(220900000000000000000000*s^4 + 470000000000000000000*s^3 + 470250044180000000000*s^2 + 500000047000000000*s + 249999953025002209))
ans =
7812500000000000*symsum(exp(t*root(s4^4 + (179290771484375*s4^3)/84266662597656256 + (3587723115386963*s4^2)/1685333251953125120 + (195312518359375*s4)/86289062500000006144 + 7812498532031319/6903125000000000491520, s4, k))/(16*(2753906250000000000*root(s4^4 + (179290771484375*s4^3)/84266662597656256 + (3587723115386963*s4^2)/1685333251953125120 + (195312518359375*s4)/86289062500000006144 + 7812498532031319/6903125000000000491520, s4, k)^2 + 1725781250000000122880*root(s4^4 + (179290771484375*s4^3)/84266662597656256 + (3587723115386963*s4^2)/1685333251953125120 + (195312518359375*s4)/86289062500000006144 + 7812498532031319/6903125000000000491520, s4, k)^3 + 1836914235078125056*root(s4^4 + (179290771484375*s4^3)/84266662597656256 + (3587723115386963*s4^2)/1685333251953125120 + (195312518359375*s4)/86289062500000006144 + 7812498532031319/6903125000000000491520, s4, k) + 976562591796875)), k, 1, 4) + 7351563190312500000*symsum((exp(root(s4^4 + (179290771484375*s4^3)/84266662597656256 + (3587723115386963*s4^2)/1685333251953125120 + (195312518359375*s4)/86289062500000006144 + 7812498532031319/6903125000000000491520, s4, k)*t)*root(s4^4 + (179290771484375*s4^3)/84266662597656256 + (3587723115386963*s4^2)/1685333251953125120 + (195312518359375*s4)/86289062500000006144 + 7812498532031319/6903125000000000491520, s4, k))/(16*(1836914235078125056*root(s4^4 + (179290771484375*s4^3)/84266662597656256 + (3587723115386963*s4^2)/1685333251953125120 + (195312518359375*s4)/86289062500000006144 + 7812498532031319/6903125000000000491520, s4, k) + 2753906250000000000*root(s4^4 + (179290771484375*s4^3)/84266662597656256 + (3587723115386963*s4^2)/1685333251953125120 + (195312518359375*s4)/86289062500000006144 + 7812498532031319/6903125000000000491520, s4, k)^2 + 1725781250000000122880*root(s4^4 + (179290771484375*s4^3)/84266662597656256 + (3587723115386963*s4^2)/1685333251953125120 + (195312518359375*s4)/86289062500000006144 + 7812498532031319/6903125000000000491520, s4, k)^3 + 976562591796875)), k, 1, 4) + 14687500000000000000*symsum((exp(t*root(s4^4 + (179290771484375*s4^3)/84266662597656256 + (3587723115386963*s4^2)/1685333251953125120 + (195312518359375*s4)/86289062500000006144 + 7812498532031319/6903125000000000491520, s4, k))*root(s4^4 + (179290771484375*s4^3)/84266662597656256 + (3587723115386963*s4^2)/1685333251953125120 + (195312518359375*s4)/86289062500000006144 + 7812498532031319/6903125000000000491520, s4, k)^2)/(16*(2753906250000000000*root(s4^4 + (179290771484375*s4^3)/84266662597656256 + (3587723115386963*s4^2)/1685333251953125120 + (195312518359375*s4)/86289062500000006144 + 7812498532031319/6903125000000000491520, s4, k)^2 + 1725781250000000122880*root(s4^4 + (179290771484375*s4^3)/84266662597656256 + (3587723115386963*s4^2)/1685333251953125120 + (195312518359375*s4)/86289062500000006144 + 7812498532031319/6903125000000000491520, s4, k)^3 + 1836914235078125056*root(s4^4 + (179290771484375*s4^3)/84266662597656256 + (3587723115386963*s4^2)/1685333251953125120 + (195312518359375*s4)/86289062500000006144 + 7812498532031319/6903125000000000491520, s4, k) + 976562591796875)), k, 1, 4) + 6903125000000000000000*symsum((exp(t*root(s4^4 + (179290771484375*s4^3)/84266662597656256 + (3587723115386963*s4^2)/1685333251953125120 + (195312518359375*s4)/86289062500000006144 + 7812498532031319/6903125000000000491520, s4, k))*root(s4^4 + (179290771484375*s4^3)/84266662597656256 + (3587723115386963*s4^2)/1685333251953125120 + (195312518359375*s4)/86289062500000006144 + 7812498532031319/6903125000000000491520, s4, k)^3)/(16*(2753906250000000000*root(s4^4 + (179290771484375*s4^3)/84266662597656256 + (3587723115386963*s4^2)/1685333251953125120 + (195312518359375*s4)/86289062500000006144 + 7812498532031319/6903125000000000491520, s4, k)^2 + 1725781250000000122880*root(s4^4 + (179290771484375*s4^3)/84266662597656256 + (3587723115386963*s4^2)/1685333251953125120 + (195312518359375*s4)/86289062500000006144 + 7812498532031319/6903125000000000491520, s4, k)^3 + 1836914235078125056*root(s4^4 + (179290771484375*s4^3)/84266662597656256 + (3587723115386963*s4^2)/1685333251953125120 + (195312518359375*s4)/86289062500000006144 + 7812498532031319/6903125000000000491520, s4, k) + 976562591796875)), k, 1, 4)
