因式分解 1)9x^4-25y^6 2)4x^2+(x+y)^2+4x(x+y) 3)(a+2b)^2-4ab-13b^

1)9x^4-25y^6
=(3x^2+5y^3)(3x^2-5y^3)
2)4x^2+(x+y)^2+4x(x+y)
=(x+y)^2+4x(x+y)+4x^2
=[(x+y)+2x]^2
=(3x+y)^2
3)(a+2b)^2-4ab-13b^2
=a^2+4ab+4b^2-4ab-13b^2
=a^2-(3b)^2
=(a+3b)(a-3b)
4)x^2+3xy-10y^2
x 5y
x -2y
=(x+5y)(x-2y)
5)a^2b-2ab-3b
=b(a^2-2a-3)
=b(a+1)(a-3)