表达式7: StartFraction, left parenthesis, "y" minus 21 , right parenthesis Over "y" minus 11 , EndFraction equals StartFraction, left parenthesis, "x" minus 1 , right parenthesis Over "x" minus 2 , EndFractiony−21y−11=x−1x−2
7
表达式8: left parenthesis, 2 "t" Subscript, 1 , Baseline plus 1 , negative 20 "t" Subscript, 1 , Baseline plus 21 , right parenthesis2t1+1,−20t1+21
表达式10: StartFraction, left parenthesis, "y" minus 25 , right parenthesis Over "y" minus 9 , EndFraction equals StartFraction, "x" plus 3 Over "x" plus 2 , EndFractiony−25y−9=x+3x+2
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表达式11: StartFraction, left parenthesis, "y" minus 9 , right parenthesis Over "y" minus 1 , EndFraction equals StartFraction, "x" plus 2 Over "x" plus 1 , EndFractiony−9y−1=x+2x+1
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表达式12: left parenthesis, negative "t" Subscript, 1 , Baseline minus 2 , 16 "t" Subscript, 1 , Baseline plus 9 , right parenthesis−t1−2,16t1+9
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表达式13: left parenthesis, "t" Subscript, 1 , Baseline minus 2 , 9 minus 8 "t" Subscript, 1 , Baseline , right parenthesist1−2,9−8t1
