Posted by Amy~ on Wednesday, September 29, 2010 at 9:42pm.
I don't get when you use "or" or "and" in inequalities.
Like for this quadratic inequality:
x^(2) +x 12 > 0
becomes x < 4
x > 3
why is the answer {xx<4 or x>3} and not {x3<x<4} ?

Math  Henry, Wednesday, September 29, 2010 at 10:40pm
Your quadratic inequality has TWO solutions: x < 4 AND x > 3.
The 2nd arrangement where you have x in the center of the inequality is normally used with compound inequalities.

Math  MathMate, Thursday, September 30, 2010 at 12:54am
If you look at the graph, it would be clear that the part of the curve which is above the xaxis is in two separate parts, therefore the answer is
x<4 and x>3.
On the other hand if the question had been x^(2) +x 12 < 0 , then the solution will be continuous on the number line, namely 4<x<3.
See graph:
http://img529.imageshack.us/img529/2064/1285810976.png
Answer This Question
Related Questions
 Math: Inequalities  for this inequality: (x1)(x2)(x3) <0 becomes x<1 x...
 algebra final, please help  Solve (x+17)(x20)(x+8)>0 The solution set is (x...
 Math  Write an inequality? In the inequality, use both the multiplication and ...
 math  Why does the inequality sign change when both sides are multiplied or ...
 prealgebra  Solve the inequality j7<24 8+b<3 h/4>16 Treat the ...
 Algebra  1. Why does the inequality sign change when both sides of the ...
 Algebra  1. Why does the inequality sign change when both sides of the ...
 algebra  Why does the inequality sign change when both sides are multiplied or ...
 algebra  Why does the inequality sign change when both sides are multiplied or ...
 Algebra  Solve the following linear inequality graphically. x+2y<4 xy<5 ...
More Related Questions