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If alpha and beta are the …

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If alpha and beta are the zeros of a quadratic polynomial x^2-5x+k and alpha-beta =1 then find tha value of k
  • 1 answers

Gaurav Seth 5 years, 3 months ago

x2-5x+k

 Here, a=1, b=-5 and c=k 

Now, α+ β = -b/a= -(-5)/1= 5 

α*β  = c/a= k/7= k

 Now,α - β =1

 Squaring both sides, we get,

 (α - β)2=12 

⇒ α2 + β- 2αβ = 1

⇒ (α2 + β2 + 2αβ) - 4αβ = 1

⇒ (α +β)2 -4αβ =1

⇒ (5)2-4k=1

⇒ -4k= 7-25

 ⇒ -4k= -24 

⇒ k=6 So the value of k is 6. 

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