Posted by **Anonymous** on Sunday, December 26, 2010 at 6:30pm.

if the domain is the set of integers, the solution set of x^2 -3x -4<0 is what?

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**Reiny**, Sunday, December 26, 2010 at 6:38pm
What your question really asks for is,

"For what values of x does the corresponding parabola

y = x^2 - 3x - 4 fall below the x-axis?"

let's find the x-intercepts ....

x^2 - 3x - 4 = 0

(x-4)(x+1) = 0

x = -1 or x = 4

so the expression is < 0 for -1 < x < 4

or

(x+1)(x-4) < 0

( x+1 >0 AND x-4<0) OR ( x+1 < 0 AND x-4>0)

( x>-1 and x<4) OR (x<-1 AND x > 4)

x>-1 and x<4 OR (null set)

-1 < x < 4

- math -
**Anonymous**, Sunday, December 26, 2010 at 6:42pm
thank you, so anything between -1 and 4 would be my answer? (0,1,2,3)?

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**bobpursley**, Sunday, December 26, 2010 at 7:13pm
yes.

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**drwls**, Monday, December 27, 2010 at 9:28pm
Since your domain is integers, only the integers (0,1,2,3) satisfy the inequality. Otherwise, there would be an infinite number of non-integer solutions between -1 and 4.

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