# Considering the inequality

• Sep 12th 2006, 04:21 PM
killasnake
Considering the inequality
Its been awhile seen I ask a question, but I need help with this inequality question.

Consider the inequality: x^2 > -2x+15

The solution of this inequality consists of one or more of the following intervals: (- Infinity,A), (A.B), and (B, Infinity) where A<B

Find A:_____

Find B:_____

How do I solve this question? It's been awhile seen I tired to solve inequalty question. Can someone give me a crash course to solve this?
• Sep 12th 2006, 04:32 PM
Quick
Quote:

Originally Posted by killasnake
Its been awhile seen I ask a question, but I need help with this inequality question.

Consider the inequality: x^2 > -2x+15

The solution of this inequality consists of one or more of the following intervals: (- Infinity,A), (A.B), and (B, Infinity) where A<B

Find A:_____

Find B:_____

How do I solve this question? It's been awhile seen I tired to solve inequalty question. Can someone give me a crash course to solve this?

x^2>-2x+15

therefore: x^2+2x>15

thus: x^2+2x+1>16

then: (x+1)^2>16

thus: x+1<-4 or x+1>4

then: x<-5 or x>3

which can be rewritten as -infinity<x<-5 or 3<x<infinity
therefore you use intervals (-infinity,A) and (infinity,B) but not interval (A,B)
• Sep 12th 2006, 07:02 PM
killasnake
oh duh! I remember now. Thank you for explaining that!