Factor Completely please...

16x^4-81y^4


12b^2+6ab-36a^2

6x^2-30xy+24y2

9a^4+36b^4

25x^4-40x^3+16x^2

81r^4-256s^4

16(x-y)^2-9

x^4-81

x^2+3x=0