Question

If A and B are zeros of x square - 4 x + 1 then One Upon A plus one upon B minus A×B is

Answer 1

Answer:

The answer is 1

Explanation :

x² - 4x + 1 = 0

using quadratic formula

x = -b ±√4ac / 2a   ; where (a = 1 , b = -4  , c = 1 ) according to the question

   =  - ( - 4) ±√4 × 1 × 1 / 2 ×1

   =  4 ± √4 / 2

   = 4 + 2 / 2 or 4 - 2 / 2

   =  6 / 2 = 3 ⇒A OR 2 / 2 = 1 ⇒ B

 according to question :

 1 / A  +  1/ B - 1 / AB

= 1/3 + 1 / 1 - 1/3

=  1

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