Homer has made mistake in step 2
When you complete the square, you need to add the values to both sides of equation
<em><u>Solution:</u></em>
<em><u>Given equation of circle:</u></em>

Let us first calculate center and radius and find out where he did the mistake
<em><u>Step 1:</u></em>
Group the terms

<em><u>Step 2:</u></em>

But homers step 2 is:

So homer has made mistake in this step
When you complete the square, you need to add the values to both sides of equation
But homer did not add 49 and 1 to right side of equation
Correct steps are:

Comparing general equation of circle,

Therefore, center is ( 7, -1) and radius is 8.66