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avatar+1855 

Find the sum of the squares of the roots of $2x^2+4x-1=x^2-8x+3$.

 Jun 27, 2024
 #1
avatar+1950 
+1

First, let's combine all like terms for x and move all terms to one side. We have that

x2+12x4=0

 

Using the quadratic equation, we have that

x=12±12241(4)21

x=2106x=2106

 

Now, we can use a handy trick to solve this problem. We have that

(2106)2+(2106)2

 

Expanding and distributing in our values, we have

2410+76+4(10)2+12106(2106)

 

All the radicals basically cancel out. In the end, we are left with 152. 

 

So 152 is our answer. 

 

Thanks! :)

 Jun 27, 2024
 #2
avatar+14 
+1

Simplifying we get x2+12x4=0. Using the quadratic formula we find the roots to be 6+210 and 6210. Taking their squares, we get 36+410+40 and 36410+40. Adding them together, we get 152

 Jun 27, 2024
 #3
avatar+130466 
+1

Let the roots be a,b

 

Product of the roots  = ab =  -4   →  2ab = -8

 

Sum of the roots =  a + b = -12     square both sides

 

a^2 + b^2 + 2ab = 144

 

a^2 + b^2 - 8 =144

 

a^2 + b^2 =  152

 

 

cool cool cool

 Jun 27, 2024

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