+0  
 
0
71
1
avatar

A. Use the fundamental theorem of algebra to determine the number of roots for 2x^2+4x+7

B. What are the roots of 2x^2+4x+7? Show your work

Guest Oct 26, 2017
Sort: 

1+0 Answers

 #1
avatar+78744 
+1

Because the degree is two, we either have two real roots or two complex roots

 

The roots are non-real because the discriminant is < 0

 

2x^2  + 4x +  7  = 0   subtract 7 from both sides

 

2x^2  +  4x  = -7

 

2 (x ^2 + 2x)  = -7    divide both sides by 2

 

x^2 + 2x   =  -7/2

 

Take 1/2 of 2  = 1.....square it  =  1   add it to both sides

 

 x^2 + 2x + 1  =  -7/2 + 1   factor the left, simplify the right

 

(x + 1) ^2  =  -5/2       take both roots

 

x + 1  =  ± √[ -5/2 ]    subtract 1  and simplify the right

 

x  = ± √[5/2] i    - 1  

 

 

cool cool cool

CPhill  Oct 26, 2017

3 Online Users

We use cookies to personalise content and ads, to provide social media features and to analyse our traffic. We also share information about your use of our site with our social media, advertising and analytics partners.  See details