44. Упростите выражения: 1) \(\frac{9c^2-16}{16-24c+9c^2}\); 2) \(\frac{16x^2-24xy+9y^2}{9y^2-16x^2}\); 3) \(\frac{4x^2-4xy+y^2}{y^2-4x^2}\).

1. \[9c^2-16=(3c-4)(3c+4),\qquad 16-24c+9c^2=(3c-4)^2.\]
   \[\frac{9c^2-16}{16-24c+9c^2}=\frac{3c+4}{3c-4}.\]
2. \[16x^2-24xy+9y^2=(4x-3y)^2,\]
   \[9y^2-16x^2=(3y-4x)(3y+4x)=-(4x-3y)(4x+3y).\]
   \[\frac{16x^2-24xy+9y^2}{9y^2-16x^2}=-\frac{4x-3y}{4x+3y}.\]
3. \[4x^2-4xy+y^2=(2x-y)^2,\qquad y^2-4x^2=(y-2x)(y+2x).\]
   \[\frac{4x^2-4xy+y^2}{y^2-4x^2}=-\frac{2x-y}{2x+y}.\]

Ответ: 1) \(\frac{3c+4}{3c-4}\); 2) \(-\frac{4x-3y}{4x+3y}\); 3) \(-\frac{2x-y}{2x+y}\).