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For what values of $j$ does the equation $(2x+7)(x-5) = -43 + jx$ have exactly one real solution? Express your answer as a list of numbers, separated by commas.

 Jun 22, 2020
 #1
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(2x + 7)  ( x - 5)   =  -43 +  jx         expand

 

2x^2  -8x  - 35  =  -43 + jx         rearrange as

 

2x^2 - ( 8 + j)x  + 8  = 0

 

This will have one real  root  if the discriminant   =  0   ....so....

 

(8 + j)^2    - 4(2) ( 8)   =  0

 

j^2  + 16j + 9   - 64   = 0

 

j^2  + 16j  - 55    =   0

 

j = -8 + sqrt(119), -8 - sqrt(119)

 Jan 10, 2021

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