Представьте в виде произведения :
1) (а-5)^2- 16b^2 ;
2) x^2 - y^2 - 5x - 5y;
3) 27- x^9;

(a-5)²-16b²=(a-5)²-(4b)²=((a-5)+4b)((a-5)-4b)=(a-5+4b)(a-5-4b)x²-y²-5x-5y=(x²-y²)+(-5x-5y)=(x+y)(x-y)-5(x+y)=(x+y)((x-y)-5)=(x+y)(x-y-5)27-x⁹=3³-(x³)³=(3-x³)(3²+3x³+(x³)²)=(3-x³)(9+3x³+x⁶)