Aloha :)
$$P(x;y;z)=\red{\overline{xy}}+x\,\overline y\,z+\overline x\,yz+\green{\overline{\overline x\,y}}+\overline x\,\overline y\,z$$$$\phantom{P(x;y;z)}=\red{\overline x+\overline y}+x\,\overline y\,z+\overline x\,yz+\green{x+\overline y}+\overline x\,\overline y\,z$$$$\phantom{P(x;y;z)}=\underbrace{(\red{\overline x}+\green x)}_{=1}+\red{\overline y}+x\,\overline y\,z+\overline x\,yz+\green{\overline y}+\overline x\,\overline y\,z=1$$