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# Help Me please.

+1
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7
+1405

Help Me please.

Equations: solve for x

x4+x2-20=0

Mar 5, 2018

### 6+0 Answers

#2
+1405
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But i think the answer is this:

-2,2,i√5,-i√5

is this correct?

Mar 5, 2018
#3
+100571
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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    }

Mar 5, 2018
#4
+1405
+1

do I have to include the brackets in my answer?

Mar 5, 2018
#5
+100571
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No....I just did that for convenience, Manuel....your solutions are correct  !!!

CPhill  Mar 5, 2018
#6
+1405
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Thank you Cphill

You are a Math saver!!

Mar 5, 2018
#7
+100571
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HAHAHA!!!!....don't know about that...but...I do know a few answers, here and there...

CPhill  Mar 5, 2018