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# P3 maths integration question watch

1. i'm doing a past paper at the mo and thereis a question i can't do. plaeaze would some maths genius in here help me

by using the substition u=tanx to findthe value of

\$ (with limits pi/6 and 0) (1+tan²x)/(1-tan²x) dx

giving ur answer in logarithmic form.

where \$ means intergral
pi means (3.14....)

thanx
2. (Original post by DLo)
i'm doing a past paper at the mo and thereis a question i can't do. plaeaze would some maths genius in here help me

by using the substition u=tanx to findthe value of

\$ (with limits pi/6 and 0) (1+tan²x)/(1-tan²x) dx

giving ur answer in logarithmic form.

where \$ means intergral
pi means (3.14....)

thanx
1+tan²x will simplify to a fimiliar identity and du/dx will give u sec²x.
Can u carry on?
3. Sub it in, multiply by dx/du and you get

INT 1/(1 - u²) du

Use partial fraction to get INT A/(1 + u) + B/(1 - u) du (obviously find A and B) Then integrate

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