The Student Room Group

Coordinate Geometry

A circle with centre at the origin has radius 2 rt 5 . A straight line has equation y =2x + k and meets the circle at two distinct points. Find the possible values of k .
What have you tried? There should be a worked example in your textbook somewhere...
(But given how often this particular question gets asked, my assumption might be wrong?)

That said, I have suspicion that, if you know the method but still didn't quite get the answer, there's a high chance you've messed up the algebra. In fact, this problem is particularly known for finicky algebra.
(edited 2 months ago)

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