A) 5с²-125 = 5(с²-25) = 5(с-5)(с+5)
B) 16m²-7mn+9n²+31mn = 16m²+24mn+9n² = (4m)²-2*4m*3n+(3n)² = (4m+3n)²
C) 2a²-ab-b² = 2a²+ab-2ab-b² = a(2a+b)-b(2a+b) = (a-b)(2a+b)
A) 5с²-125 = 5(с²-25) = 5(с-5)(с+5)
B) 16m²-7mn+9n²+31mn = 16m²+24mn+9n² = (4m)²-2*4m*3n+(3n)² = (4m+3n)²
C) 2a²-ab-b² = 2a²+ab-2ab-b² = a(2a+b)-b(2a+b) = (a-b)(2a+b)