J Jojofelyx Well-Known Member Joined Jan 3, 2021 Messages 410 Gender Female HSC 1998 Jul 16, 2021 #1 Thanks! Attachments Screen Shot 2021-07-16 at 9.05.29 pm.png 13.6 KB Views: 64
B B1andB2 oui oui baguette Joined Nov 6, 2019 Messages 576 Location cuddles lane Gender Undisclosed HSC N/A Jul 16, 2021 #2 differentiate x=5tantheta and rearrange to get dx=5sec^2theta dtheta replace x's with given sub and dx with above factorise 25 out of denominator to use trig identity to simplify then just simplify indices and stuff should cross out, you'll probably be able to follow from there oh yeah don't forget to replace any lone thetas (if you end up with one) by rearranging given sub if needed/ draw triangle to get stuff back in x form 2 marks is a bit stingy though Last edited: Jul 16, 2021
differentiate x=5tantheta and rearrange to get dx=5sec^2theta dtheta replace x's with given sub and dx with above factorise 25 out of denominator to use trig identity to simplify then just simplify indices and stuff should cross out, you'll probably be able to follow from there oh yeah don't forget to replace any lone thetas (if you end up with one) by rearranging given sub if needed/ draw triangle to get stuff back in x form 2 marks is a bit stingy though
D Drongoski Well-Known Member Joined Feb 22, 2009 Messages 4,238 Gender Male HSC N/A Jul 17, 2021 #3 If we can ignore substitution: Last edited: Jul 17, 2021
J Jojofelyx Well-Known Member Joined Jan 3, 2021 Messages 410 Gender Female HSC 1998 Jul 17, 2021 #4 Drongoski said: If we can ignore substitution: Click to expand... I did it using a simpler sub of u= 25 + x^2, it was just the specific one which tripped me up thanks though!
Drongoski said: If we can ignore substitution: Click to expand... I did it using a simpler sub of u= 25 + x^2, it was just the specific one which tripped me up thanks though!
C CM_Tutor Moderator Moderator Joined Mar 11, 2004 Messages 2,644 Gender Male HSC N/A Jul 17, 2021 #5 @Jojofelyx , make sure you can do trig substitutions too, questions can require them and there is not always an alternative substitution option for you to use.
@Jojofelyx , make sure you can do trig substitutions too, questions can require them and there is not always an alternative substitution option for you to use.
C CM_Tutor Moderator Moderator Joined Mar 11, 2004 Messages 2,644 Gender Male HSC N/A Jul 17, 2021 #6 In this case: Now, noting that we can see that