Solution: Original formula =(x+9)(x-9)

2. 1/4×a？ -B?

Solution: original formula = 1/4(a+b)(a-b)

3.9(x-y)？ -25

Solution: Original formula =[3(x-y)+5][3(x-y)-5]

4.(x？ -y)？ -(2y-2)？

Solution: Original formula =[(x? -y)+(2y-2)][(x？ -y)-(2y-2)]

=(x？ -y+2y-2)(x？ -y-2y+2)

=(x？ +y-2)(x？ -3y+2)

5.x^4-8 1

Solution: The original formula =(x? +9)(x？ -9)

=(x？ +9)(x+3)(x-3)

6.3x^6-3x？

Solution: Original formula =3x? (x^4- 1)

=3x？ (x？ + 1)(x？ - 1)

=3x？ (x？ + 1)(x+ 1)(x- 1)

7.(a？ -2b)？ -( 1-2b)？

Solution: Original formula =[(a? -2b)+( 1-2b)][(a？ -2b)-( 1-2b)]

=(a？ -2b+ 1-2b)(a？ -2b- 1+2b)

=(a？ -4b+ 1)(a？ - 1)

=(a？ -4 b+ 1)(a+ 1)(a- 1)

8.9x^4-36y？

Solution: the original formula = 9 (x 4-4 y? )

=9(x？ +2y)(x？ -2y)