Article View: ba.mathweb
Article #41hard problems
From: Mr. X
Date: Mon, 23 Feb 1998 00:00
Date: Mon, 23 Feb 1998 00:00
31 lines
2114 bytes
2114 bytes
Here are some hare math problems that I've been working on. I've had
tremendous difficulty with them. If you figure some of them out, please
e-mail me with the answer and the work used to find the answer at
boot-leg@ix.netcom.com . Here they are:
1) A certain virus has infected 10,000 people in a geographical area. The
treatment for the virus can reduce the number of infected peopleby 10% each
week, so the decrease is exponential. The following data has been collected
for the first three weeks. How many weeks will pass until only 10% of the
original 10,000 have the virus?
(week #, # of people infected): (0,10000); (1,9000); (2,8100); (3,7300)
2) Write each as a single logarithm.
a) 3ln x + ln(pie) - 2ln(x-2)
b) (1/2)ln x + (1/2)ln y - ln(x-5)
3) If we define (2n +1)! to mean the product of (1)(2)(3). . .(2n + 1) and
(2n + 1)!! to mean the product of (1)(3)(5). . .(2n + 1), express (2n + 1)!!
in terms of (2n + 1)!
4) If (ax)^log a = (bx)^log b , a,b>0, a is not equal to b, a is not equal
to 1, b is not equal to 1, and the logarithmic base is the same throughout,
express x in terms of a and b
5) If f is a function of x only, and q is a function of y only, determine f
and g suck that the log f + log g = log(1+z) where z = x + xy + y
In this last problem there are logs with different bases than ten, so I will
be using this format: logA B=log base A of B.
EX: log2 pie = log base 2 of pie.
EX: log(pie) 2 = log base pie of 2
6) Prove algebraically, without using logarithm tables or calculators,
that:
a) (1/log2 pie) + (1/log5 pie) > 2
b) (1/log2 pie) + (1/log(pie) 2) >2
Technical Details
Message-ID:
<6ct1fq$jan@dfw-ixnews6.ix.netcom.com>Path:
arc1-ca.pugleaf.net!unknown!not-for-mailShow Full Headers
Complete Article Headers
X-Google-Language: ENGLISH,ASCII-7-bit X-Google-Thread: 10bf1c,d00a0f1f706a7dd7,start X-Google-Attributes: gid10bf1c,public From: "Mr. X" <boot-leg@ix.netcom.com> Subject: hard problems Date: 1998/02/23 Message-ID: <6ct1fq$jan@dfw-ixnews6.ix.netcom.com> X-Deja-AN: 327994283 X-MimeOLE: Produced By Microsoft MimeOLE V4.71.1712.3 Organization: Netcom X-NETCOM-Date: Mon Feb 23 5:41:46 PM CST 1998 Newsgroups: ba.mathweb