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Find all values of x such that x(x+7.5)>38.5 . Answer with interval notation.

Guest Nov 30, 2018
 #1
avatar+14579 
+2

Expand to x^2+7.5x - 38.5 > 0    Use quadratic formula to find x = -11  and 3.5

 

These are the zeros of a normally upright parabola.....so x outside of these numbers, the fxn would be > 0

     BETWEEN ( & including the values) the values of the function are zero or negative

 

so          -11 >x>3.5

ElectricPavlov  Nov 30, 2018
edited by ElectricPavlov  Nov 30, 2018
 #4
avatar+456 
+1

You are right but it should be in interval notation.

CoolStuffYT  Dec 1, 2018
 #2
avatar+14579 
+2

Here is the graph:

 

ElectricPavlov  Nov 30, 2018
 #3
avatar+456 
+1

EP is right except in Interval Notation it is

(-11, 3.5), thanks EP

 

You are very welcome!

:P

CoolStuffYT  Dec 1, 2018
 #5
avatar+14579 
+1

Thanx for pointing that out ! cheeky

BUT ACTUALLY, we need interval notation with a disjunction....

   it should look like this:

(-inf, -11) U (3.5, +inf)  

 

Sorry for the confusion !   

ElectricPavlov  Dec 1, 2018
edited by ElectricPavlov  Dec 1, 2018

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