Question 4221
are your terms all powers? or is a*4 really 4a etc?


if they are coefficients then:


{{{matrix(5,4, 4,2,9,7,21, 2,5,5,4,11.5, 6,3,5,3,15.5, 8,4,6,6,22)}}}


Now, the trouble is working out a 4x4 determinant. I do not have the time to walk though or type this here, so i advise you look on the web for a step-by-step guide to 4x4 matrices.


Anyway, Cramer's rule - ideal for this question.


work out the determinant, D for {{{matrix(4,4, 4,2,9,7, 2,5,5,4, 6,3,5,3, 8,4,6,6)}}}


then work out the determinant, Da for {{{matrix(4,4, 21,2,9,7, 11.5,5,5,4, 15.5,3,5,3, 22,4,6,6)}}}


Then do the same for Db, Dc and Dd -->


{{{matrix(4,4, 4,21,9,7, 2,11.5,5,4, 6,15.5,5,3, 8,22,6,6)}}}
{{{matrix(4,4, 4,2,21,7, 2,5,11.5,4, 6,3,15.5,3, 8,4,22,6)}}}
{{{matrix(4,4, 4,2,9,21, 2,5,5,11.5, 6,3,5,15.5, 8,4,6,22)}}}


If you are still sane, then:


a = Da/D

b = Db/D

c = Dc/D

d = Dd/D


jon