Help me please meh

Find the domain of the following expression: 1/(√x)-2

If 30 lb of rice and 30 lb of potatoes cost ? $27.60? , and 20 lb of rice and 12 lb of potatoes cost ? $15.04? , how much will 10 lb of rice and 50 lb of potatoes? cost?

In which direction does the left side of the graph of this function point? a(x) = 3x - x2 + 4x - 2