
Originally Posted by
Sandstorm
To the bold: Good luck convincing the piece of paper on my desk.
To the italics: How so? That's what I was given on the paper. Can you explain further?
That's odd. I originally assumed you were using a graphing calculator or maybe computer software. Then one of the roots isn't even in the range that you're graphing.
Anyway, I misspoke. Space is infinite. Graphs are a finite representation to show a particular region of space, and ideally you would pick the location/size/resolution of what you're representing to be meaningful. (And even that explanation is wrong, if you ask a math major. But I'm not a math major.)
The roots of
ax^2+bx+c
are
(-b +/- sqrt(b^2 - 4ac))/(2a)
using the quadratic equation
Those roots are your "x-values", and by definition of being roots, your "y-values" there had better be 0.
You were leaving out the whole radical.
The roots are roughly 1 and 15.
Precisely, they are 8 +/- sqrt(46)
as the Wolfram Alpha link says
So at least one of them works out in your -10 to 10 window of x-values. Maybe you're not meant to care about the other one if you're meant to be doing it graphically in that window.
Last edited by ForgotMyName; 11-06-2010 at 07:02 AM.
Wow. I've been gone a very long time indeed. So much has changed.