Remember that |z - w| is the distance between z and w in the complex plane.
So |z - 3 + i| ≤ 5
<=> |z - (3 - i)| ≤ 5
i.e. z is within 5 units of the point 3-i.
So draw a circle of radius 5, centred at 3-i, and fill it in.
|z+i| ≤ |z-i|
says the distance from z to -i is less than or equal to the distance from z to +i.
In other words, take the perpendicular bisector of the line segment joining -i and +i; we want all points that are on this line or on the -i side of the line.
In this case the perpendicular bisector is just the real axis, so we just want everything on or below the real axis.
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Remember that |z - w| is the distance between z and w in the complex plane.
So |z - 3 + i| ≤ 5
<=> |z - (3 - i)| ≤ 5
i.e. z is within 5 units of the point 3-i.
So draw a circle of radius 5, centred at 3-i, and fill it in.
|z+i| ≤ |z-i|
says the distance from z to -i is less than or equal to the distance from z to +i.
In other words, take the perpendicular bisector of the line segment joining -i and +i; we want all points that are on this line or on the -i side of the line.
In this case the perpendicular bisector is just the real axis, so we just want everything on or below the real axis.