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Ray Vickson
#3
Feb26-12, 07:28 PM
Sci Advisor
HW Helper
Thanks
P: 4,958
Quote Quote by truongson243 View Post
1. The problem statement, all variables and given/known data

For every x over ℝ, find min, max of following expression

2. Relevant equations

y=8x4/(x2+1)2+4x/(x2+1)+1

3. The attempt at a solution
I've graphed it but it's really complex. How can I find that points? Thank you so much :)
You need to use Calculus, setting the derivative to zero. That gives you a 4th degree polynomial to solve; its two real roots correspond to the max and min. (They are the roots of the polynomial x4 - 8x3 - 1.)

RGV