Wang Libo's answer to Sophie's Junior College 2 H2 Maths question.

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Wang Libo
Wang Libo's answer
22 answers (A Helpful Person)
1st
Just sub everything. The only thing needs to pay attention is the range of u has to be changed accordingly.
Sophie
Sophie
7 years ago
Thank you, but then why couldn’t I use dx/du to make dx into du? I will get (9-u)^2
Wang Libo
Wang Libo
7 years ago
See my 2nd answer