SOLUTION: find two points on the y-axis that are a distance of 5 units from (4,2)

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Question 640175: find two points on the y-axis that are a distance of 5 units from (4,2)
Answer by reviewermath(1029) About Me  (Show Source):
You can put this solution on YOUR website!
Let (0,k) be the point on the y-axis.
Using distance formula
sqrt%28%284+-+0%29%5E2+%2B+%282+-+k%29%5E2%29+=+5
sqrt%2816+%2B+k%5E2+-+4k+%2B+4%29+=+5
sqrt%28k%5E2+-+4k+%2B+20%29+=+5, gt the square of both sides
k%5E2+-+4k+%2B+20+=+25
k%5E2+-+4k+-+5+=+0
%28k-5%29%28k%2B1%29+=+0
k = 5 or -1
The points are (0,5) and (0,-1).