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NDA 2013
Exam
NDA
Year
2013
Subject
Mathematics
Chapter
Quadratic Equation

NDA 2013 · Mathematics · Quadratic Equation

The quadratic equation x^2+b x+4=0 will have real roots if

The quadratic equation x2+bx+4=0x^2+b x+4=0 will have real roots if

Options

  1. Ab≤−4b \leq-4 only
  2. Bb≥4b \geq 4 only
  3. C−4<b<4-4 < b < 4
  4. Db≤−4,b≥4b \leq-4, b \geq 4

Correct answer

D. b≤−4,b≥4b \leq-4, b \geq 4

Step-by-step solution

Quadratic equation have real roots if discriminant D>0b2−4.1.4≥0\mathrm{D} > 0b^2-4.1.4 \geq 0 or, b2≥16b^2 \geq 16 or, b≥4b \geq 4 and b≤−4b \leq-4
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