



 
Hi Tiawo, I think you mean x^{3} + 4x^{2} + 20 x  7 over (x  1)^{2}(x^{2} + 8). The task is to write this in partial fraction form as Writing this sum of three fractions with a common denominator give a numerator which must equal the numerator of the original fraction. Thus
Substituting x = 1 in this equation gives B = 2 and hence the equation simplifies to
Equating polynomial coefficients leads to the linear system
This system yields A = 3, C = 2 and D = 1. I hope this helps,  


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