The answer to #1 is 0.
In order to find the answer to this one (or any of these problems, simply follow the order of operations. In the case of #1, we first want to stick the 0 in for a and then continue.
Since these two numbers cancel, you will get the answer as 0. For the rest of these, follow the basic steps provided by your teacher in PEMDAS.
(x - 4 )² + ( y - 2 )² = 5 → d
the equation of a circle in standard form is
(x - a )² + ( y - b)² = r²
where (a , b) are the coordinates of the centre and r is the radius
the centre is at the midpoint of the endpoints of the diameter and the radius is the distance from the centre to either of the 2 endpoints of the diameter.
to find the centre use the midpoint formula
(a , b) = [ (6 + 2) ,
(3 + 1 )] = (4 , 2)
to find r use the distance formula with points (4 , 2) and (6 ,3 )
r = √(6 - 4)² + ( 3 - 2)² = √( 4 + 1 ) = √5 ⇒ r² = 5
(x - 4)² + (y - 2)² = 5 is the equation