Is the sentence true or false?

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

is a first-order differential equation 

What is the order of a differential equation with the form  $\frac{d^2y}{dx^2}=4x+2$ ?

What is the order of a differential equation with the form

$\frac{99d^2y}{dx^2}+\frac{76dy}{dx}-y=0$ ?

What is the order of a differential equation with the form$\frac{15d^3y}{dx^3}-\frac{76dy}{dx}+52y=0?$

Fill in the blank:

The differential equation  dy/dx +12y=13 is a _________order differential equation

What is the order of a differential equation with the form $5\frac{d^2y}{dx^2}-\frac{9d^2y}{dx^2}+\frac{6dy}{dx}+2y=0$ ?

Fill in the blank:

The differential equation $e^xy+\frac{d^3y}{dx^3}+\frac{d^2y}{dx^2}=e^x$ ,is of  _________order

What is the order of a differential equation with the form $\frac{d^2y}{dx^2}+\frac{pdy}{dx}+qy=0$ ?

What is the order of a differential equation with the form

$\frac{d^3y}{dx^3}+r\frac{d^2y}{dx^2}+\frac{pdy}{dx}+qy=0$

What is the order of a differential equation?