
PreCalculus PreCalculus Math Forum 
 LinkBack  Thread Tools  Display Modes 
December 23rd, 2017, 02:49 PM  #11 
Global Moderator Joined: Dec 2006 Posts: 20,635 Thanks: 2080 
The problem doesn't say so. However, let's treat the current ungrammatical wording ("where xintercept") as though it were "where the only $x$intercept". It's now easy to find examples that show that the statements numbered 1, 2, and 4 are incorrect. With a little more trouble (because 9/8 is fairly close to, but less than, $\frac{2\sqrt3}{3}$), one can also choose a value of $a$ such that the statement numbered 4 is incorrect. The statement numbered 5 is correct. This can be proved in various ways. It's equivalent to the condition $4 < 27b^2\!$. Note that your early assertion that both factors must equate to zero is incorrect. For there to be only one real zero, the discriminant of the second factor must be negative (so that it has no real zero). 

Tags 
correct, cubic, find, function, statement 
Thread Tools  
Display Modes  

Similar Threads  
Thread  Thread Starter  Forum  Replies  Last Post 
Cubic function  GabrielT  PreCalculus  3  November 20th, 2016 08:59 AM 
Roots of Cubic Function  eddybob123  Number Theory  7  June 25th, 2014 02:54 PM 
Is this mathematic logic statement is correct?  danoc93  Applied Math  16  October 2nd, 2013 03:47 PM 
Which is The Correct Statement (function/set)  newyear498  Applied Math  9  April 4th, 2012 06:06 AM 
Is this statement correct?  NeuroFuzzy  Calculus  1  September 29th, 2010 01:14 PM 