表达式3: "a" equals left bracket, 1 , 2 , ...2 1 , right bracketa=1,2,...21
3
表达式4: left parenthesis, "x" plus StartRoot, 2 , EndRoot "a" minus "b" , right parenthesis squared plus left parenthesis, "y" minus StartRoot, 2 , EndRoot "a" plus "b" , right parenthesis squared equals left parenthesis, "a" , right parenthesis squaredx+2a−b2+y−2a+b2=a2
4
表达式5: left parenthesis, "x" minus StartRoot, 2 , EndRoot "a" plus "b" , right parenthesis squared plus left parenthesis, "y" minus StartRoot, 2 , EndRoot "a" plus "b" , right parenthesis squared equals left parenthesis, "a" , right parenthesis squaredx−2a+b2+y−2a+b2=a2