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QJEEM19Ma91c5: JEE Main 2019 Mathematics - Class 11 JEEM19Ma91c5 Solution: The number of integral values of m for which the equation (1 +…

The number of integral values of m for which the equation

(1 + m2 )x2 – 2(1 + 3m)x + (1 + 8m) = 0 has no real root is :

Multiple Choice Options

  • A 2
  • B infinitely many
  • C 1
  • D 3

Step-by-Step Verified Solution

(1 + m2 )x2 – 2(1 + 3m)x + (1 + 8m) = 0

Given equation has no real solution,

∴\therefore Discriminant (D) < 0

⇒\Rightarrow 4(1 + 3m)2 - 4(1 + m2)(1 + 8m) < 0

⇒\Rightarrow 4[9m2 + 6m + 1 - 8m - 1 - 8m3 - m2] < 0

⇒\Rightarrow -8m3 + 8m2 - 2m < 0

⇒\Rightarrow -2m(4m2 - 4m + 1) < 0

⇒\Rightarrow m(2m - 1)2 > 0

∴\therefore m > 0 and m ≠\ne 12{{1 \over 2}}

So we can say number of integral values of m are infinitely many.

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