The substitution required to reduce the differential equation $t^2 d x+\left(x^2-t x+t^2\right) d t=0$ to a differential equation which can be solved by variables separable method is

The equation which represents the system of parabolas whose axis is parallel to $Y$-axis satisfies the differential equation.

If $\cos x \frac{d y}{d x}=y \sin x-1, x \neq(2 n+1) \frac{\pi}{2}, n \in Z$ is the differential equation corresponding to the curve $y=f(x)$ and $f(0)=1$, then $f(x)$

The general solution of the differential equation $2 d x+d y=(6 x y+4 x-3 y) d x$ is