Find the product and show your solution.
1. (x+9) (x²-9x+81)=
2. (y²-7) (y⁴-7y²+49)=
3. (x²-5) (x⁴+5x²+25)=
4. (8x-9y) (64x²+72xy+81y²)=
5. (10m-11) (100m²+110m+121)=​​