(1)4a(2x-y)^2-36a
=4a[(2x-y)^2-9]
=4a(2x-y+3)(2x-y-3)
(2)20a^2b^2-2ab+5
不能分解
(3)3a(x^2+4)^2-48ax^2
=3a[(x^2+4)^2-16x^2]
=3a(x^2+4x+4)(x^2-4x+4)
=3a(x+2)^2(x-2)^2