表达式3: "k" equals left bracket, StartFraction, "a" minus "b" Over 2 , EndFraction ... StartFraction, "a" plus "b" Over 2 , EndFraction , right bracketk=a−b2...a+b2
equals=
00
11
22
33
44
55
66
77
88
99
1010
3
表达式4: StartFraction, left parenthesis, "y" minus "k" , right parenthesis Over "x" , EndFraction equals StartFraction, "k" Over "k" minus "a" , EndFractiony−kx=kk−a