SOLUTION: I have no idea how to do circles and find the center and radius. A circle has the equation of 7x^2 + 7y^2 + 42x +28y - 84 = 0. Graph the circle using the center (h,k) and the r

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Question 779859: I have no idea how to do circles and find the center and radius.
A circle has the equation of 7x^2 + 7y^2 + 42x +28y - 84 = 0.
Graph the circle using the center (h,k) and the radius r. Find the intercepts, if any of the graph. Thank you in advance
Answer by solver91311(24713) (Show Source):
You can put this solution on YOUR website!

Complete the squares:

Step 1. Add the additive inverse of the constant term to both sides.

Step 2: Multiply by the reciprocal of the coefficients on the and terms

Step 3: Rearrange with spaces so that you can create the sum of two quadratic trinomials, one in x and one in y

Step 4: Divide the first degree x term coefficient by 2, square the result and add to both sides of the equation. 6 divided by 2 is 3, 3 squared is 9, so:

Step 5: Repeat for the y terms:

Step 6: Sum the constants:

Step 7: Factor the two perfect square trinomials in the LHS:

Rewrite:

Since the equation of a circle centered at with radius is:

You can determine by inspection.

John

Egw to Beta kai to Sigma
My calculator said it, I believe it, that settles it