Science, asked by kaurrubika, 10 months ago

Q7 If (-4) is a root of the quadratic eqn. X
2
+Px-4=0 and the equation 2X2
+P X+k=0 has equal roots. Find
the value of k.

Answers

Answered by abhi569
22

Answer:

9/8

Explanation:

  - 4 is a root of x^2 + Px - 4 = 0, it means it will satisfy the given condition. So for x = - 4 equation will remain same :

  ⇒ ( - 4 )^2 + P( - 4 ) - 4 = 0

  ⇒ 16 - 4P - 4 = 0

  ⇒ 16 - 4 = 4P

  ⇒ 12 = 4P

  ⇒ 3 = P

 2x^2 + Px + k = 0 has equal roots which means its discriminant is 0.

   ⇒ P^2 - 4( 2 * k ) = 0

   ⇒ ( 3 )^2 - 8k = 0    { P = 3 }

   ⇒ 9 - 8k = 0

   ⇒ 9 = 8k

   ⇒ 9/8 = k

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