Posted by Anonymous on .
if the domain is the set of integers, the solution set of x^2 3x 4<0 is what?

math 
Reiny,
What your question really asks for is,
"For what values of x does the corresponding parabola
y = x^2  3x  4 fall below the xaxis?"
let's find the xintercepts ....
x^2  3x  4 = 0
(x4)(x+1) = 0
x = 1 or x = 4
so the expression is < 0 for 1 < x < 4
or
(x+1)(x4) < 0
( x+1 >0 AND x4<0) OR ( x+1 < 0 AND x4>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,
thank you, so anything between 1 and 4 would be my answer? (0,1,2,3)?

math 
bobpursley,
yes.

math 
drwls,
Since your domain is integers, only the integers (0,1,2,3) satisfy the inequality. Otherwise, there would be an infinite number of noninteger solutions between 1 and 4.