# Search results

1. ### catalyst question

What is the end all definition of a catalyst? Conc acids are used to speed up the rate of reaction/lower activation energy/increase rate of reaction both ways in equilibrium, but surely if conc acids are dehydrating agents then they are actually getting involved in the equlibrium, e.g. favouring...
2. ### quick prob

general solution of cos4x + cos2x = sqrt2 . cos^2(x) + 1/sqrt2 . sin2x
3. ### greatest term tk+1/tk

hey ive seen a few questions that use different definitions of the tk+1 term to get the greatest coefficient the way i was shown u define the tk+1 as nCk and then tk as nCk-1 and then have tk+1/tk >= 1 its a bit weird though cos in the trial there was a question to prove this, and i...
4. ### Volume questions (cylindrical)

By taking cylindrical shells find the volume enclosed in the region enclosed by (x-1)^2 + y^2 = 1 I ended up getting like the integral of x(2x-x^2)^1/2 I couldn't get it. Is my integration shice or is there a trick to these kinds of questions, like 2 semi-circles or something. if...
5. ### integration: partial fractions question

integ x secx tanx dx I got: x secx - ln|tan(45 + x/2)| + C 45 being in degrees I'm pretty sure it's right, but am not sure how the book got x secx - ln(secx + tanx) + C Is my answer wrong? How did they get theres? Thanks