Mathematics
Which of the following equations has two real and distinct roots ?
2x2 - = 0
x2 + x - 5 = 0
x2 + 3x + = 0
7x2 - 3x + 1 = 0
Quadratic Equations
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Answer
For an equation having real and distinct roots :
b2 - 4ac > 0
Comparing equation (1) with ax2 + bx + c, we get :
a = 2, b =
Substituting values in b2 - 4ac,
⇒
⇒
⇒ 0.
Comparing equation (2) with ax2 + bx + c, we get :
a = 1, b = 1 and c = -5.
Substituting values in b2 - 4ac,
⇒ 12 - 4 × 1 × (-5)
⇒ 1 + 20
⇒ 21.
Since, b2 - 4ac > 21.
∴ x2 + x - 5 = 0 has real and distinct roots.
Hence, Option 2 is the correct option.
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