Question

de o centro e o raio da circunferência x2 +y2-2x-2y-7=0

Answer 1

x² +y²-2x-2y-7=0

x²-2x+y²-2y-7=0
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completando os quadrados

x²-2x+1-1+y²-2y+1-1-7=0

(x²-2x+1)-1+(y²-2y+1)-1-7=0

(x+1)²-1+(y-1)²-1-7=0

(x+1)²+(y-1)²-9=0

(x+1)²+(y-1)²=9

(x-1)²+(y-1)²=3²    ........(x-b)²+(y-b)²=r²

Centro (a,b) ==>Centro (1,1)  e o raio =3