Разложите на множители:
а)
3abc + ab(a + b) + bc(b + c) + ac(a + c) + ab + bc + ac = abc + abc + abc + ab(a + b) + bc(b + c) + ac(a + c) + ab + bc + ac = (abc + ab(a + b)) + (abc + bc(b + c)) + (abc + ac(a + c)) + ab + bc + ac = ab(c + a + b) + bc(a + b + c) + ac(b + a + c) + (ab + bc + ac) = (a + b + c)(ab + bc + ac) + (ab + bc + ac) = (ab + bc + ac)(a + b + c + 1)