表达式6: left parenthesis, StartFraction, "v" Subscript, 1 , Baseline Over "k" "h" , EndFraction left parenthesis, StartFraction, "g" Over "k" , EndFraction plus "u" , right parenthesis left parenthesis, "t" plus StartFraction, 1 Over "k" , EndFraction left parenthesis, "e" Superscript, negative "k" "t" , Baseline minus 1 , right parenthesis , right parenthesis minus StartFraction, "v" Subscript, 1 , Baseline Over 2 "h" "k" , EndFraction "g" "t" squared , StartFraction, 1 Over "k" , EndFraction left parenthesis, StartFraction, "g" Over "k" , EndFraction plus "u" , right parenthesis left parenthesis, 1 minus "e" Superscript, negative "k" "t" , Baseline , right parenthesis minus StartFraction, "g" Over "k" , EndFraction "t" , right parenthesisv1khgk+ut+1ke−kt−1−v12hkgt2,1kgk+u1−e−kt−gkt
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定义域t最小值：
less than or equal to "t" less than or equal to≤t≤
