SOLUTION: Find K so that the circle X2+y2+kx+4y-5 will pas through the point (5,1).

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Question 739122: Find K so that the circle X2+y2+kx+4y-5 will pas through the point (5,1).
Answer by MathLover1(20849) About Me  (Show Source):
You can put this solution on YOUR website!
x%5E2%2By%5E2%2Bkx%2B4y-5+=0 will pas through the point (5,1).
kx=5-x%5E2-y%5E2-4y if x=5 and y=1
k%2A5=5-5%5E2-1%5E2-4%2A1
5k=5-25-1-4

5k=-25
k=-5
x%5E2%2By%5E2-5x%2B4y-5+=0
%28x%5E2-5x%2B25%2F4%29-25%2F4%2B%28y%5E2%2B4y%2B4%29-4+=5
%28x-5%2F2%29%5E2%2B%28y%2B2%29%5E2=5%2B25%2F4%2B4
%28x-5%2F2%29%5E2%2B%28y%2B2%29%5E2=5%2B25%2F4%2B4
%28x-5%2F2%29%5E2%2B%28y%2B2%29%5E2=9%2B25%2F4
%28x-5%2F2%29%5E2%2B%28y%2B2%29%5E2=36%2F4%2B25%2F4
%28x-5%2F2%29%5E2%2B%28y%2B2%29%5E2=61%2F4
center: (5%2F2,-2)
radius: sqrt%2861%2F4%29=3.9