SOLUTION: how do you find the radius of the circle x^2+y^2-2x+4y=4?

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Question 385641: how do you find the radius of the circle x^2+y^2-2x+4y=4?
Answer by solver91311(24713) About Me  (Show Source):
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Complete the square on each of the variables:



Group variable types:



Start with the x term. Divide the coefficient by 2, square the result, add the squared result to both sides of the equation. -2 divided by 2 is -1, -1 squared is 1, add 1 to both sides:



Repeat the process for y:



Factor the two perfect square trinomials in the LHS and collect the constants in the RHS:



The constant term in the RHS is now the radius squared. The radius is the positive square root of the constant.

John

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