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Find all points $(x,y)$ that are $5$ units away from the point $(2,7)$ and that lie on the line $y = 5x - 28.$

 Aug 9, 2024
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First, let's make some observations about this question. 

All points 5 units away from point (2, 7) would make a circle with center (2, 7) and radius 5. 

The formula for that circle would look something like (x2)2+(y7)2=25

 

Now, combining that with the second equation, and we get a system. 

Subsituting out y with the x values in the line equation, we get 

(x2)2+(5x35)2=25

 

Simplifying, and we get

13x2177x+602=0

 

Using the quadratic equation, we find two values of x. We get

x=7x=8613

 

Plugging these x values into the second equation where we isolated y, we get that y=7,y=6613

 

So our final two answers are (7, 7) and (86/13, 66/13)

 

Thanks! :)

 Aug 9, 2024
edited by NotThatSmart  Aug 9, 2024

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