а²+б²+3с²+2аб+4ас+4бс = а²+2аб+б²+3с²+4с(a+б) = (a + b)² + 3c² + 3c(a+b) + c(a + b) = (a + b)² + 3c(a + b) + 3c² + c(a+b) = (a + b)(a + b + 3c) + c(a + b + 3c) = (a + b + c)( a + b + 3c)
а²+б²+3с²+2аб+4ас+4бс = а²+2аб+б²+3с²+4с(a+б) = (a + b)² + 3c² + 3c(a+b) + c(a + b) = (a + b)² + 3c(a + b) + 3c² + c(a+b) = (a + b)(a + b + 3c) + c(a + b + 3c) = (a + b + c)( a + b + 3c)