+0  
 
+1
205
7
avatar+1405 

Help Me please.

 

Equations: solve for x

 

x4+x2-20=0

 Mar 5, 2018
 #2
avatar+1405 
+1

But i think the answer is this:

 

-2,2,i√5,-i√5

is this correct?

 Mar 5, 2018
 #3
avatar+95884 
+1

x^4   + x^2 - 20  =  0      factor

 

(x^2 + 5) (x^2 - 4)  = 0

 

(x^2 + 5)  ( x - 2) ( x + 2)  = 0

 

Set each factor to 0...and solve for x

 

x  - 2  = 0       x +  2  = 0       x^2 + 5  = 0

x  =  2             x  =  -2           x^2  =  -5         take both roots

                                              x = ±√-5

                                              x  = ±√5 i

 

So....the solutions are

 

x  =   { -2, 2, √5 i ,  - √5 i    }

 

 

 

cool cool cool

 Mar 5, 2018
 #4
avatar+1405 
+1

do I have to include the brackets in my answer?

 Mar 5, 2018
 #5
avatar+95884 
0

No....I just did that for convenience, Manuel....your solutions are correct  !!!

 

 

cool cool cool

CPhill  Mar 5, 2018
 #6
avatar+1405 
+1

Thank you Cphill

 

You are a Math saver!!

 Mar 5, 2018
 #7
avatar+95884 
0

HAHAHA!!!!....don't know about that...but...I do know a few answers, here and there...

 

 

cool cool cool

CPhill  Mar 5, 2018

12 Online Users

New Privacy Policy

We use cookies to personalise content and advertisements and to analyse access to our website. Furthermore, our partners for online advertising receive information about your use of our website.
For more information: our cookie policy and privacy policy.