For the Bernoulli equation y′+p(x)y=q(x)yny' + p(x)y = q(x)y^ny′+p(x)y=q(x)yn, which substitution is valid for all n≠1n \neq 1n=1?
v=ynv = y^nv=yn
v=y1−nv = y^{1-n}v=y1−n
v=ln(y)v = \ln(y)v=ln(y)
v=eyv = e^yv=ey