運算式 6: "x" squared plus left parenthesis, "y" plus 2 , right parenthesis squared equals left parenthesis, "r" plus 2 "a" , right parenthesis squaredx2+y+22=r+2a2
6
運算式 7: "x" squared plus left parenthesis, "y" minus 2 , right parenthesis squared equals left parenthesis, "r" minus 2 "a" , right parenthesis squaredx2+y−22=r−2a2
7
運算式 8: "x" squared plus left parenthesis, "y" plus 3 , right parenthesis squared equals left parenthesis, "r" plus 3 "a" , right parenthesis squaredx2+y+32=r+3a2
8
運算式 9: "x" squared plus left parenthesis, "y" minus 3 , right parenthesis squared equals left parenthesis, "r" minus 3 "a" , right parenthesis squaredx2+y−32=r−3a2