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x^2 - 18 + 79 = 0

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1 Answer

If the equation is x^2 - 18x + 79 = 0
 
Completing the Square : move the number 79 on the other side of equal sign and use formula as indicated
x^2 +bx +(b/2)^2  = c + (b/2)^2
 
x^2 - 18x  (-18/2)^2 = -70 + (-18/2)^2
x^2 - 18x + 81 = -79 + 81
x^2 - 18x + 81 = 2
(x - 9) (x - 9) = 2
(x - 9)^2 = 2
 
Now solve for x by applying square root
 
√(x-9)^2 = ±√(2)
 
x-9 = ±√(2)
  +9    +9
 
x = 9 ± √(2)
 
 

Comments

Priti,
 
did you mean x^2 +bx +(b/2)^2  = -c + (b/2)^2  ?
 

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