Appeared in: 2026 (2 sets)
Which of the following is not a Linear Differential Equation ?
(A) $(1 + x^2) dy + 2xy dx = \cot x dx$
(B) $y + \frac{d}{dx}(xy) = x (\sin x + \log x)$
(C) $x (1 + y^2) dx - y (1 + x^2) dy = 0$
(D) $y dx - (x + 3y^2) dy = 0$