Consider a theory with a single dimensionless coupling g whose beta function takes the form β(g)=b1g2+b2g3+…. Now consider a new definition of the coupling of the form g~=g+c2g2+….
a) Show that β(g~)=b1g~2+b2g~3+….
b) Generalize this result to the case of multiple dimensionless couplings.