Question 901042
The zeros are also critical values.  Check the sign of each interval.


The zeros are 1 and -3.  You can see this because f is shown in its factored form.  The intervals on x to check signs for f are:
{{{-infinity<x<-3}}};
{{{-3<x<1}}};
{{{1<x<infinity}}}.
Pick ANY value in each interval and test the sign of f(x).


You should find, according to each listed interval:
Positive, negative, negative.


Can you conclude what that means?  Note that around the value x=1, the value for f is still negative.  Sign did not change there.





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{{{graph(300,300,-6,3,-6,6,-2(x-1)^2(x+3))}}}