(b)
i do not know number 2 sorry
3. (A)
hope it helps have a great day :D
Answer:
Step-by-step explanation:
Given that:

if we assume that x is zero, then
,
i.e the radius of the circle goes from -6 to +6, Similarly, if we assume that z is zero, then
,
,
. This implies that
describes the circle with radius 6
is an equation at region which consist of those points whose distance from the centre is at least with radius -6 and at most 6.
Therefore, the region is the solid cylinder of radius 6, where the Y axis is also the axis of the cylinder.
21=27+x
If you replace x with -6 then your answer will be 21!!