Answer:
a) 1/27
b) 16
c) 1/8
Step-by-step explanation:
a) 
One of the properties of the exponents tells us that when we have a negative exponent we can express it in terms of its positive exponent by turning it into the denominator (and changing its sign), so we would have:

And now, solving for x = 9 we have:

b) 
This is already a positive rational exponent so we are just going to substitute the value of y = 8 into the expression

c) 
Using the same property we used in a) we have:

And now, solving for z = 16 we have:

Answer:
$1.4 B per year
Step-by-step explanation:
Step-by-step explanation:
√a is defined only when a >= 0.
Therefore for √4x * √(x + 2) to be defined, both 4x and x + 2 must be non-negative.
When 4x >= 0, x >= 0.
When x + 2 >= 0, x >= -2.
x >= 0 and x >= -2, therefore we have x >= 0. (D)