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Answer:
x^2 +y^2 +6x -18y +65 = 0
Step-by-step explanation:
The short of it is that you're being asked to rewrite each of these standard-form equations into general form: f(x,y) = 0.
It can save you a little effort if you recall that the square of a binomial is ...
(a +b)² = a² +2ab +b²
Otherwise, you would use the distributive property to get ...
(a +b)(a +b) = a(a +b) +b(a +b)
= a² +ab +ab +b²
= a² +2ab +b²
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For the given equation, expanding the squares gives ...
(x +3)² +(y -9)² = 5²
(x² +6x +9) +(y² -18y +81) = 25 . . . . . expand the squares
x^2 +y^2 +6x -18y +65 = 0 . . . . . . . . subtract 25; put in order of decreasing powers of the variables
