Question 1066507
x^2-3x-4=0
(x-4)(x+1)= 0
x= 4
x=-1
-1 and 4 are critical points.  They divide the number line into three areas: test less than the smallest, between them, and greater than the largest.
For x <-1 try -2.  f(-2) >0
between the two points, try 0 f(0)< 0, does not work
greater than 4, try 5 f(5)=6
(-1, 4)
{{{graph(300,300,-10,10,-10,10,x^2-3x-4)}}}