1) The integrating factor of xdydx−y=x4−3x is A) x B) log x C) 1/x D) -x Answer: Option CExplanation:Since xdydx−y=x4−3x .'. dydx−yx=x3−3 Hence IF = e∫pdx = e−∫1xdx = e−logx = 1/x