Posted by **Mota** on Friday, January 22, 2010 at 7:49am.

find the exact values when :

x^2+2x >= 5

- math -
**bobpursley**, Friday, January 22, 2010 at 8:57am
x^2+2x-5=>0

Well, the issue is what are the factors on the left.

Using the quadratic equation

x=(-2+- sqrt (4+4*5))/2=-1+-sqrt6

(x+1-sqrt6)(x+1+sqrt6)>=0

Well, for the left side to be > 0, both factors have to be positive or negative.

Take x=-100000. That works. So negative x have to be considered.

Case I

x+1-sqrt 6<0 And x+1+sqrt6<0

x<-1+sqrt6 AND x<=-1-sqrt6

Since it has to be AND

then x<=-1-sqrt6

Now, when are both positive:

Case II

x+1-sqrt6>=0 AND x+1-sqrt6>=0

x>-1+sqrt6 AND x>-1+sqrt6

Since that is AND, then

x>-1+sqrt6

So finally, the exact values are

-1+sqrt6<x OR

x<-1-sqrt6

Check my logic.

## Answer This Question

## Related Questions

- calculus - g(x)=(x^3)-(3x^2)+17 a)find and classify all critical points of g(x) ...
- MATH - 1.)Find the exact solution algebriacally, if possible: (PLEASE SHOW ALL ...
- Math - 1. Let (-7, 4) be a point on the terminal side of (theta). Find the exact...
- trig exact vales - Find the exact values requested. No decimal approximations. ...
- math - how do you do the steps for this problem find two exact values for sin(...
- Math/Trig - Find two exact values of sin(cosˉ¹ √5/6)
- Calc 1: Max/Min - Find values for a and b so the function f(x)= ax*e^bx has the ...
- Calculus - estimate the absolute maximum and minimum values of f if any, on the ...
- Precalculus - The exponential function f(x)=6(4)^2x+2 can be written in the ...
- math - use exact values of the sin,cos and tan of (pi/3) and (pi/6)(which I ...

More Related Questions