[Maxima] distributing sums

[Edward A. Romana]

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How do I distribute a sun such that

sun((x[j]+y[j]+x[j]*y[j]),j,a,b) => 

sum(x[j],j,a,b)+sum(y[j],j,a,b)+sum(x[j]y[j],j,a,b);


 
Ed

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