Разложите на множители:

1) 28-7y^2

2) - 11x^2+22x-11

3) x^3y+8y

4) (y^2-1) ^2-9

5) 2m^3-18m

6) 7m^2+14mn+7n^2

7) 6n^3+6m^3

8) 16m^4-81n^4

1) 28-7y^2 = 7 (4-у²) = 7 (2-у) (2+у) = - 7 (у+2) (у-2)

2) - 11x^2+22x-11 = - 11 (х²-2 х+1) = - 11 (х-1) ²

3) x^3y+8y = у (х³+8) = у (х+2) (х²-2 х+4)

4) (y^2-1) ^2-9 = (у²-1) ²-3² = (у²-1-3) (у²-1+3) = (у²-4) (у²+2) = (у²+2) (у+2) (у-2)

5) 2m^3-18m = 2m (m²-9) = 2m (m-3) (m+3)

6) 7m^2+14mn+7n^2 = 7 (m²+2mn+n²) = 7 (m+n) ²

7) 6n^3+6m^3 = 6 (n³+m³) = 6 (n+m) (n²-mn-m²)

8) 16m^4-81n^4 = (4m²) ² - (9n²) ² = (4m²+9n²) (4m²-9n²) = (4m²+9n²) (2m+3n) (2m-3n)