Differential Equations

To convert Euler-Cauchy's differential equation $x^2 \frac{d^2 y}{dx^2} + a x \frac{dy}{dx} + b y = 0$ into a linear differential equation with constant coefficients, the standard substitution used is:

Options:

• (A) $x = e^z$ or $z = \ln x$
• (B) $y = e^z$
• (C) $x = z^2$
• (D) $y = x v$