推 king911015:最後一行我不懂~= =? 218.175.88.171 03/21 12:14
※ 引述《king911015 (早已放棄愛上你)》之銘言：
: x f(t)
: Find a function f and a unmber a such that 6 + ∫ ----- dt =2√x for allx>0.
: a t^2
x f(t)
( 6 + ∫ ----- dt )' = (2√x)'
a t^2
f(x) 1 x^2
=> ------ = ----- => f(x) = ------
x^2 √x √x
^^^^^^^^^^^^^^^^
x 1
∫ ----- d* = 2√x - 6 => 2√a = 6 => √a = 3 => a = 9
a √* ^^^^^^^^
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