A decimal number and a fraction can be compared one number is greater than Less than or equal to other numbers
I attached your answer below...
The midpoint of the points ( 4, 5.5 ) and ( 4, 10.5 ) is the center of the circle:
C =

C = ( 4, 8 ), h=4, k=8
r =

r = 2.5
The equation of the circle in standard form:
( x - h )² + ( y - k )² = r²
( x - 4 )² + ( y - 8 ) = 6.25
Why not? Because every math system you've ever worked with has obeyed these properties! You have never dealt with a system where a×b did not in fact equal b×a, for instance, or where (a×b)×c did not equal a×(b×c). Which is why the properties probably seem somewhat pointless to you. Don't worry about their "relevance" for now; just make sure you can keep the properties straight so you can pass the next test. The lesson below explains how I kept track of the properties.
the construction of fields of formal infinite series in several variables, generalizing the classical notion of formal Laurent series in one variable. Our discussion addresses the field operations for these series (addition, multiplication, and division), the composition, and includes an implicit function theorem.
(PDF) Formal Laurent series in several variables. Available from: https://www.researchgate.net/publication/259130653_Formal_Laurent_series_in_several_variables [accessed Oct 08 2018].