Identify the integrating factor μ(x)\mu(x)μ(x) for the linear first-order ODE: y′+3xy=xy' + \frac{3}{x}y = xy′+x3y=x.
μ(x)=x3\mu(x) = x^3μ(x)=x3
μ(x)=3x\mu(x) = 3xμ(x)=3x
μ(x)=ln∣x∣\mu(x) = \ln|x|μ(x)=ln∣x∣
μ(x)=3x2\mu(x) = 3x^2μ(x)=3x2