Take the logarithm and then regression.

ln(y) = ln(a) + b ln(x1) + c ln(x2) + d ln(x3) + e ln(x4)

Notice that coefficients and exponents are very different sorts of things. SO what do you mean? David Booth

Mr. David Eugene Booth

Thank you for caring

I have experimental work results where the main function Y depending upon many independent variables xi , so I want to make an equation form like what I published to predict the main function y at any change in the independent variables xi.

With my respect