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 Algebra Pre-Algebra and Basic Algebra Math Forum

 September 7th, 2007, 06:28 AM #1 Newbie   Joined: Sep 2007 Posts: 1 Thanks: 0 A few problems that I'm stuck on.. 1. Simplify: ln (3x^2 - 9x) + ln (1 / 3x) 2. Solve for x: (x + 3) / (x - 2) > 0 3. Solve for x: Sqrt(x^2 + 1) - (x^2) / Sqrt(x^2 + 1) = 1/2 Help in solving these would be much appreciated. These are from a review sheet in my Calculus class covering Pre-Calc concepts and none of these are in the book. Thank you. September 7th, 2007, 07:39 AM #2 Global Moderator   Joined: Nov 2006 From: UTC -5 Posts: 16,046 Thanks: 938 Math Focus: Number theory, computational mathematics, combinatorics, FOM, symbolic logic, TCS, algorithms Re: A few problems that I'm stuck on.. For #1, remember that ln(xy) = ln(x) + ln(y). For #2, solve as though an equality, then check a point on each side to see which way the inequality 'points'. September 7th, 2007, 07:59 AM #3 Global Moderator   Joined: Dec 2006 Posts: 21,038 Thanks: 2274 Re: A few problems that I'm stuck on.. Below are some hints which should make things easy for you. 1. Use the rule ln(A) + ln(B) = ln(AB) (where A > 0, B > 0). 2. Note that x is real and non-zero. Multiply both sides by (x - 2)�. The graph of the resulting left-hand side is a parabola. 3. Multiply both sides by 2?(x� + 1), then square both sides of the resulting equation. Tags problems, stuck Thread Tools Show Printable Version Email this Page Display Modes Linear Mode Switch to Hybrid Mode Switch to Threaded Mode Similar Threads Thread Thread Starter Forum Replies Last Post kaybees17 Advanced Statistics 2 October 14th, 2013 09:19 PM jkh1919 Calculus 3 November 3rd, 2012 12:18 PM hagtos Elementary Math 2 June 21st, 2012 08:35 AM jaigooroo Algebra 1 July 21st, 2008 12:16 PM redwood Physics 2 October 27th, 2007 06:42 AM

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