Question 620182
(x-1)(x+4)<0 | Change < to = and find the zeroes by solving for x (each factor).<P>
x=1, x=-4 |Set up and test intervals based on those zeroes:  x < -4, -4 < x < 1, x > 1<P>
x < -4, choose -4:  (-5-1)(-5+4) = -6*-1 = 6 which is not < 0.  This interval doesn't work.<P>
-4 < x < 1, choose 0: (0-1)(0+4) = -1*4 = -4 < 0.  This interval works.<P>
x  >1, choose 2:  (2-1)(2+4) = 1*6 = 6 not < 0.  This interval doesn't work.<P>
The answer is -4 < x < 1.<P>
If you know parabolas, or graph this, you will see this is less than 0 between the zeroes.  Check out the graph (at the bottom).
*[invoke quadratic "x", 1, 3, -4 ]

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