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Wilma and Greg were trying to solve the quadratic equation x^2 + bx + c = 0.Wilma wrote down the wrong value of b (but her value of c was correct), and found the roots to be 1 and 8. Greg wrote down the wrong value of c (but his value of b was correct), and found the roots to be 1 and -4. What are the actual roots of x^2 + bx + c = 0?

 Jan 25, 2021
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The product  of   Wilma's  roots  = c/1 =  c

So   1 * 8   =  8    = c

 

The sum of Greg's roots  =    -b/1  = -b

So    1 +  -4  =  -3

So b =  3

 

 

So  the polynomial is

 

x^2   + 3x   +  8   =   0

 

Using the  quadratic  formula  the roots are

 

( -3   ± √  (3)^2  - 4*8 ))  / 2   =   ( -3 ± √-23 )  / 2  =     (-3 ±  i √23) / 2

 

 

cool cool cool

 Jan 25, 2021

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