9 . Consider the differential equation dx dt
2
� , where t , 0 �x cos�t x � .
1 ( a ) Express � 2 dx as an indefinite integral of t . x [ 2 ]
( b ) Hence , using the substitution u� �t to find the expression of 1 x , giving the answer in terms of t .
It is given that x � 1 when t � 2.5.
( c ) Find the expression of x .
[ 3 ]
[ 3 ]
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