b)25x²-10xy+y²+15x-3y=(5x-y)²+3(5x-y)=(5x-y)*(5x-y+3)
c)a³-27+6a²-18a=(a-3)*(a²+3a+9)+6a*(a-3)=(a-3)*(a²+3a+9+6a)=(a-3)*(a²+9a+9)
b)25x²-10xy+y²+15x-3y=(5x-y)²+3(5x-y)=(5x-y)*(5x-y+3)
c)a³-27+6a²-18a=(a-3)*(a²+3a+9)+6a*(a-3)=(a-3)*(a²+3a+9+6a)=(a-3)*(a²+9a+9)