assertAlmostEqual(radicalAxis({x: 3, y: 2, r: 5}, {x: 8, y: 7, r: 4}), {a: -0.7071067811865475, b: -0.7071067811865475, c: 7.707463914933368});

Is this even correct? The midpoint 5.5, 4.5 is clearly inside the radical axis, but 5.5*a + 4.5+b + c is around 0.636396, not 0.

Return an object with the properties a, b, and c representing the coefficients of the radical axis equation in the form ax + by + c = 0.

The description forgot to mention that a^2 + b^2 = 1 and c >= 0. Without this there are infinitely many solutions of (a, b, c).

Edit: Actually c >= 0 is not the correct criteria, in random tests the sign sometimes differ. Anyways because of this both (a, b, c) and (-a, -b, -c) are valid solutions.

Hi,

The kata is technically ok (at least at first glance), but that's unfrotunately a duplicate. We already have this kind of task, so you should unpublish it.

Cheers

Binomial expansion is a duplicate: https://www.codewars.com/kata/540d0fdd3b6532e5c3000b5b

There are no random tests. Actual tests are the same as sample tests.

What is a invalid expression is not defined. Why is (5y+7) invalid? It is because of y, or the lack of exponent?

(Also, you didn't specify what should be done in this case.)

It's very obvious expressions like 42x^33^1 are not valid expressions. (Why are you concatenating 3 terms directly?)