CHBE 251 Lecture 31: CHBE 251 L31

Evaluate the following derivatives: (a) d/dx (cosx+isinx), (b) d/dx sin^(2) x , (c) d/dx ln x , (d) d/dx e^(ix) , (e) d/dx e^(-x^2) , (f) d/dx x^(2)cosx , (g) d/dx cosy , where y=tan x

1. A 20g sample of Th-277 decays to 17g in 3 days. What is the rate constant for the decay of this isotope?

a) 1.9 d^-1 b) 0.49 d^-1 c) 1.50 d^-1 d) 0.054 d^-1 e) 0.12 d^-1

2. If two-thirds of a radon-86 sample decays in 6.1 days, what is the half-life of this isotope?

a) 1.18 d b) 0.41 d c) 0.10 d d) 4.2 d e) 3.8 d