My Math Forum my exam question

 Algebra Pre-Algebra and Basic Algebra Math Forum

 May 13th, 2015, 07:46 AM #1 Newbie   Joined: Oct 2014 From: England Posts: 12 Thanks: 0 my exam question I had an exam today morning and I didn't answer this question because I can't even tell if it is inequalities or coordinate geometry 2x^2-x -3=k has no real roots. Find the set of possible values of k.
 May 13th, 2015, 10:42 AM #2 Senior Member     Joined: Mar 2011 From: Chicago, IL Posts: 214 Thanks: 77 Let's write this quadratic equation in standard form: $\displaystyle 2x^2-x-(k+3)=0$ The discriminant of it is: $\displaystyle 1+4(2)(k+3)=8k+25$ Quadratic equation has no real roots if the discriminant is lesser than 0: $\displaystyle 8k+25<0$ $\displaystyle k<-\frac{25}{8}$
May 15th, 2015, 11:58 AM   #3
Newbie

Joined: Oct 2014
From: England

Posts: 12
Thanks: 0

Quote:
 Originally Posted by skaa Let's write this quadratic equation in standard form: $\displaystyle 2x^2-x-(k+3)=0$ The discriminant of it is: $\displaystyle 1+4(2)(k+3)=8k+25$ Quadratic equation has no real roots if the discriminant is lesser than 0: $\displaystyle 8k+25<0$ $\displaystyle k<-\frac{25}{8}$
Thanks, I wish I gave that answer

 Tags exam, question

 Thread Tools Display Modes Linear Mode

 Similar Threads Thread Thread Starter Forum Replies Last Post BonaviaFx Physics 1 April 7th, 2015 12:47 AM OriaG Calculus 1 February 10th, 2013 09:55 AM csoles Elementary Math 2 March 21st, 2012 09:22 PM samuraibob Linear Algebra 2 October 28th, 2010 08:06 AM Stilianos Calculus 2 November 5th, 2009 03:11 PM

 Contact - Home - Forums - Cryptocurrency Forum - Top