The number of four letter words that can be formed using the letters of the word BARRACK is :

If |z $$-$$ 3 + 2i| $$ \le $$ 4 then the difference between the greatest value and the least value of |z| is :

If the system of linear equations
x + ay + z = 3
x + 2y + 2z = 6
x + 5y + 3z = b
has no solution, then :

The coefficien of x¹⁰ in the expansion of (1 + x)²(1 + x²)³(1 + x³)⁴ is equal to :