分解因式```

=（4x^2-9）(x^2-1)
=(2x+3)(2x-3)(x+1)(x-1)

十字相乘法:
4x4-13x2+9
=(4x2-9)(x2-1)
=(2x-3)(2x=3)(x+1)(x-1)

4x4-13x2+9
= x^2 -1
4x^2 -9(十字相乘法）

=(x^2-1)(4x^2-9)

=(x-1)(x+1)(2x-3)(2x+3)

x^4=y^2(y>=0);
4y^2-13y+9
=(4y-9)(y-1)
=[(2x)^2-3^2](x^2-1)
=(2x-3)(2x+3)(x-1)(x+1)

hj05004123
的对

（4x^2-9）(x^2-1)
(2x+3)(2x-3)(x+1)(x-1)