Given the relations

employee (name, salary, deptno), and
department (deptno, deptname, address)

Which of the following queries cannot be expressed using the basic relational algebra operations $$\left(\sigma, \pi,\times ,\Join, \cup, \cap,-\right)$$?

B⁺-trees are preferred to binary trees in databases because

The number $$43$$ in $$2's$$ complement representation is

The simultaneous equations on the Boolean variables $$x, y, z$$ and $$w,$$ $$$x+y+z=1$$$ $$$xy=0$$$ $$$xz+w=1$$$ $$$xy + \overline z \overline w = 0$$$
have the following for $$x, y, z$$ and $$w,$$ respectively.