表达式3: left parenthesis, "x" plus 10 minus "a" , right parenthesis squared plus left parenthesis, "y" plus "a" , right parenthesis squared equals "a" squaredx+10−a2+y+a2=a2
3
表达式4: left parenthesis, "x" plus 10 minus "a" , right parenthesis squared plus left parenthesis, "y" plus 10 minus "a" , right parenthesis squared equals "a" squaredx+10−a2+y+10−a2=a2
4
表达式5: left parenthesis, "x" plus "a" , right parenthesis squared plus left parenthesis, "y" plus 10 minus "a" , right parenthesis squared equals "a" squaredx+a2+y+10−a2=a2
