For the Bernoulli equation y′+2y=xy3y' + 2y = xy^3y′+2y=xy3, what is the linear equation for v=y−2v = y^{-2}v=y−2?
v′−4v=−2xv' - 4v = -2xv′−4v=−2x
v′+4v=−2xv' + 4v = -2xv′+4v=−2x
v′−2v=−xv' - 2v = -xv′−2v=−x
v′+2v=xv' + 2v = xv′+2v=x