Question 753830
1. Given f(x)=2x^3+x^2-8x-4. 
(a) Find the x-intercepts of f.
use rational roots theorem to solve: 
....0...|.....2......1......-8......-4....
....1...|.....2......3......-5......-9...
....2...|.....2......5.......2........0 (2 is a root)
f(x)=(x-2)(2x^2+5x+2)
f(x)=(x-1)(2x+1)(x+2)
roots are: 1, -1/2, -2 (x-intercepts)
..
(b) Find f(0).
f(0)=-4
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(c) Use test points within the intervals formed by the x-intercepts to determine the sign of f(x) in the interval. 
number line:
<...-...-2...+....-1/2...-....1....+.....>

(d) Graph f(x). 
{{{ graph( 300, 300, -4, 4, -10, 10,2x^3+x^2-8x-4) }}}