differential equation

Is the following equation a differential equation?

 $\frac{\text{d}y}{\text{d}x}=3x+4y$  

• yes

• no

is the following equation a differential equation?

 $2y\frac{\text{d}y}{\text{d}x}=5x$  

• yes

• no

is the following equation a differential equation?
  $\frac{y}{x}=3x+5y$  

• yes

• no

 $x^{3^{ }}\frac{\text{d}y}{\text{d}x}+3x^2y=x^4$  

is the above equation a differential equation?

• yes

• no

is $x^2+^{ }y^2-2xy=\frac{y}{x}$   a differential equation?

• yes

• no

is $\frac{\text{d}y}{\text{d}x}=e^x+\ln x$  a differential equation?

• yes

• no

Is $\frac{\text{d}^2y}{\text{d}x^2}=\sin x+\cos y\frac{\text{d}y}{\text{d}x}$  a differential equation?

• yes

• no