運算式 5: "y" plus "X" minus "N" equals StartFraction, "N" minus "X" Over "X" , EndFraction left parenthesis, negative "x" , right parenthesis left brace, 0 less than "x" less than "N" , right brace left brace, 0 less than "y" less than "N" , right bracey+X−N=N−XX−x0<x<N0<y<N
5
運算式 6: StartRoot, "x" , EndRoot plus StartRoot, "y" , EndRoot equals StartRoot, "N" , EndRootx+y=N
6
運算式 7: 4 "x" "y" equals left parenthesis, "N" minus "x" minus "y" , right parenthesis squared4xy=N−x−y2
