7/6 is 1 and 1/6 (1 1/6) as a reduced fraction. 7/6 is an improper fraction. So, how many times does 6 go into 7, it goes into it one time and there is one remainder.
When taking square roots, you can't take square roots of negative roots of negative numbers. So, what will work for the domain of u(x) is what makes u(x) zero or more. We can make an inequality for that.
u(x) ≥ 0.

9x + 27 ≥ 0 by squaring both sides
9x ≥ -27
x ≥ -3
So the domain of the function is when x ≥ -3 is true.
Set is a sum of two intervals :(1,4) u [2,6]
In the first interval it is open on both sides so 1 and 4 don't belong to this interval, the second is closed so both 2 and 6 belong to interval and numbers between 2 and 6
We can write it as 1<x

summing both sets we have one set: (1,6]
so
a) represent our set
b) also represent because all numbers between 4-6 and 6 are in our set
c)also represent, all numbers are in main set
d)also represent
Volume is in cubic units, meaning the volume ix raised to the 3rd power.
If the cube is scaled by 5, then the volume is scaled by 5^3.
5^3 = 5*5*5 = 125
The new volume would be the original volume multiplied by the total increase:
64 x 125 = 8,000 cubic meters.