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junior college 2 | H2 Maths
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Sophie
Sophie

junior college 2 chevron_right H2 Maths

Hello please see the circled part! I wonder how they got into the third step in the part , I do it by (dx/du)du to convert to u. And I got (9-u)^2/u^2. Thanks in advance!

Date Posted: 6 years ago
Views: 388

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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
6 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
6 years ago
See my 2nd answer
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Wang Libo
Wang Libo's answer
22 answers (A Helpful Person)
check with your's
Sophie
Sophie
6 years ago
Understood. Thank you;)