Question 851811
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Hi,
Standard Form of an Equation of a Circle is {{{(x-h)^2 + (y-k)^2 = r^2}}} 
where Pt(h,k) is the center and r is the radius
 1 - 3 use above, substitute values given
4 & 5 Completing the Square:
4. (x-4)^2 + y^2 = -7 + 16 = 9  
   {{{(x-4)^2 + y^2 = 3^2}}}
 (x+2)^2 + (y-3)^2 = 3 + 4 + 9 = 16
   {{{(x+2)^2 + (y-3)^2 = 4^2}}}