The Student Room Group
Reply 1
if all you have to do is verify it then just substitute it in
Reply 2
I got down to
LHS = x tanx + (x^2) sec^2 x

RHS = X tanX + X^2 + (X^ 2)tan^2 x

I'm stuck. Have I done something wrong?
Reply 3
What youve done is correct. You just need to tidy up your RHS..

X tanX + X^2 + (X^ 2)tan^2 x

X tanX + X^2 [1+tan^2 X]

1 + tan^2 X = sec^2 X (from sin^2 X + cos^2 X = 1)

therefore RHS = X tan X + X^2 sec^2 X
Reply 4
Thank you so much! I've been trying to find some rule ive overlooked! Thankyou!

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