The range of y = a cot bx is

What is the standard equation of a parabola that opens downward?

Determine whether each of the following equations has no graph.

In the equation  ,  the equation of the directrix is 

For the graph of y = 3 cos 2(x–1) + 4, period =

For the graph y = a sin b(x-h) + k, the period is

The number of ways to choose 3 T-shirts and 2 jackets out of 6 T-shirt and 5 jackets is

What is the standard equation of a parabola that opens upward?

Three-digit even numbers can be formed by using 1, 2, 3, 4 and 5. The number of ways in which repetition digit is allowed is

If    and    , then   is