We know that:

is an equation of a circle.
When we substitute x and y (from the pairs we have), we'll get a system of equations:

and all we have to do is solve it for a, b and r.
There will be:

From equations (II) and (III) we have:

and from (I) and (II):

Now we can easly calculate a and b:

Finally we calculate

:

And the equation of the circle is:
The reciprocal of 6/5 is D. 5/6
Reciprocal simply means swapping the position of the numbers in the fraction. The numerator becomes the denominator and the denominator becomes the numerator.
We need to get reciprocal of a fraction when division is performed.
For example: 2 ÷ 1/5
2 may be a whole number but in fraction form it is 2/1.
1st fraction = 2/1
2nd fraction = 1/5
In dividing fractions, the 1st step we need to do is to get the reciprocal of the 2nd fraction.
1/5 ⇒ 5/1
Then, we multiply the 1st fraction to the reciprocal of the 2nd fraction.
2/1 * 5/1 = 10
So, 2 ÷ 1/5 = 10
The absolute value of x is simply x and followed by the expression.
X + 1 + x + 1 <_ 2
2x + 2 <_ 2
2x <_ 0
X <_ 0
Basically all values that follow this inequality will most likely hold true.
For instance. -1.
-1 + 1 = 0
Absolute value of -2 = 2.
2 is equal to 2. This expression holds true.