Por ejemplo veamos con la primera
y´´ + 4y´ + 3y = 4 + 3x
<img src="https://tex.z-dn.net/?f=%28Ae%5E%7B2x%7D%2BBxe%5E%7B2x%7D%29%27%27%20%2B4%28Ae%5E%7B2x%7D%2BBxe%5E%7B2x%7D%29%27%20%2B%203%28Ae%5E%7B2x%7D%2BBxe%5E%7B2x%7D%29%20%3D%204%2B3x" />
<img src="https://tex.z-dn.net/?f=%282Ae%5E%7B2x%7D%2BBe%5E%7B2x%7D%2B2Bxe%5E%7B2x%7D%29%27%20%2B4%282Ae%5E%7B2x%7D%2BBe%5E%7B2x%7D%2B2Bxe%5E%7B2x%7D%29%20%2B%5C%5C%0A%2B%203%28Ae%5E%7B2x%7D%2BBxe%5E%7B2x%7D%29%20%3D%204%2B3x" />
<img src="https://tex.z-dn.net/?f=%284Ae%5E%7B2x%7D%2B2Be%5E%7B2x%7D%2B2Be%5E%7B2x%7D%2B4Bxe%5E%7B2x%7D%29%20%2B4%282Ae%5E%7B2x%7D%2BBe%5E%7B2x%7D%2B2Bxe%5E%7B2x%7D%29%20%2B%5C%5C%0A%2B%203%28Ae%5E%7B2x%7D%2BBxe%5E%7B2x%7D%29%20%3D%204%2B3x" />
y es obvio que esta no es la respuesta
y´´ - 4 y´ + 4y = 0 esta es la respuesta.