Name:
SUMMER II, 2014
MATH 142:203
QUIZ - 3
• This is an individual quiz, open notes, open textbook.
• Read each question carefully, answer each question completely, box your answers.
• Show all of your work; no credit will be given for unsupported answers.
1. ( 2 pts) Simplify:
(x2 y 7 z 3 )5
.
z 4 x8
x2 y 35 z 11 .
2. (2 pts) In terms of lnu, lnv, lnw, rewrite the following expression:
ln
u22 w4
v5w
2
.
2(22lnu − 5lnv + 3lnw).
3. (2 pts) Solve for x:
1 x4 7
= lne
7
4
(7−1 )(7x ) = 1
7x
4 −1
= 70
(x2 − 1)(x2 + 1) = 0
x = 1, x = −1.
4. (4 pts) The half-life of Plutonium-239 is 24,000 years. There are 20 grams now. How long will it
take until 30% of the original amount remains? (Round your answer to 4 decimal places.)
F = P0 ert
0.5P0 = P0 e24000r
ln(0.5)
r=
24000
0.3P0 = P0 ert
ln(0.3)
t=
r
24000ln(0.3)
= 41687.17426.
t=
ln(0.5)