What is the complete set of numbers for which f( x ) = x 3 + 2 x 2 - x is concave?

What is the complete set of numbers for which f(x) = x3 + 2x2 - x is concave?

x ≥ -2/3
x ≥ -3/2
x ≥ 3/2
x ≥ 1
None of the above

For x = 1/2 the second derivative of f(x) = 2x−2 is

3/4
100
192
25
None of the above

For x = 2, the slope of the function f(x) = x4 - 3x2 is

10
25
15
30
None of the above

The inflection point for f(x) = x3 - 3x2 + x + 5 is

x = 0
x = 1
x = -1
x = 2
None of the above

The unit cost of producing a steak dinner at the Smalltown Inn is $6. If a restaurant charges p dollars for a steak dinner, customers will demand 200 - 5p steak dinners per week. To maximize the profit earned on steak dinners, what price should the inn charge?