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If the absolute value of the difference ...

If the absolute value of the difference of the roots of the equation `x^(2) + ax + 1 = 0 "exceeds" sqrt(3a)`, then

A

`a in (-oo, -1) uu (4, oo)`

B

`a in (4, oo)`

C

`a in (-1, 4)`

D

`a in [ 0, 4)`

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The correct Answer is:
To solve the problem, we need to find the range of \( a \) such that the absolute value of the difference of the roots of the equation \( x^2 + ax + 1 = 0 \) exceeds \( \sqrt{3a} \). ### Step-by-Step Solution: 1. **Identify the Roots**: For the quadratic equation \( x^2 + ax + 1 = 0 \), we can denote the roots as \( \alpha \) and \( \beta \). 2. **Use the Formula for the Difference of Roots**: The difference of the roots can be expressed as: \[ |\alpha - \beta| = \sqrt{(\alpha + \beta)^2 - 4\alpha\beta} \] From Vieta's formulas, we know: - \( \alpha + \beta = -\frac{b}{a} = -a \) - \( \alpha \beta = \frac{c}{a} = 1 \) Substituting these into the formula gives: \[ |\alpha - \beta| = \sqrt{(-a)^2 - 4 \cdot 1} = \sqrt{a^2 - 4} \] 3. **Set Up the Inequality**: We need to find when this difference exceeds \( \sqrt{3a} \): \[ \sqrt{a^2 - 4} > \sqrt{3a} \] 4. **Square Both Sides**: To eliminate the square roots, we square both sides: \[ a^2 - 4 > 3a \] 5. **Rearrange the Inequality**: Rearranging gives: \[ a^2 - 3a - 4 > 0 \] 6. **Factor the Quadratic**: We can factor the quadratic: \[ (a - 4)(a + 1) > 0 \] 7. **Determine the Intervals**: To find the intervals where this inequality holds, we can test the intervals determined by the roots \( a = -1 \) and \( a = 4 \): - For \( a < -1 \): Choose \( a = -2 \) → \( (-2 - 4)(-2 + 1) = (-6)(-1) > 0 \) (True) - For \( -1 < a < 4 \): Choose \( a = 0 \) → \( (0 - 4)(0 + 1) = (-4)(1) < 0 \) (False) - For \( a > 4 \): Choose \( a = 5 \) → \( (5 - 4)(5 + 1) = (1)(6) > 0 \) (True) 8. **Conclusion**: The solution to the inequality \( (a - 4)(a + 1) > 0 \) is: \[ a \in (-\infty, -1) \cup (4, \infty) \] ### Final Answer: The values of \( a \) for which the absolute value of the difference of the roots exceeds \( \sqrt{3a} \) are: \[ a \in (-\infty, -1) \cup (4, \infty) \]
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OBJECTIVE RD SHARMA ENGLISH-QUADRATIC EXPRESSIONS AND EQUATIONS -Chapter Test
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  2. If a, b, c are positive real numbers, then the roots of the equation a...

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  3. If the absolute value of the difference of the roots of the equation x...

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  4. If alpha, beta be roots of the equation 375x ^(2) -25x-2=0 and s (n) =...

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  5. The quadratic equation x^(2) + (a^(2) - 2) x - 2a^(2) and x^(2) - 3x +...

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  6. The roots of ax^(2) +bx +c =0 " whose " a ne 0, b ,c in R , " are non...

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  7. The value of m for which the equation x^3-mx^2+3x-2=0 has two roots ...

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  8. If the equation formed by decreasing each root of the a x^2+b x+c=0 by...

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  9. If the roots of the equation ax^2-bx-c=0 are changed by same quantity ...

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  10. If x^2-2rprx+r=0; r=1, 2,3 are three quadratic equations of which each...

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  11. If x ^(2) + px +1 is a factor of ax ^(3) + bx +c, then:

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  12. If (x-1)^3 is a factor of x^4+ax^3+bx^2+cx-1=0 then the other factor ...

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  13. If alpha is a root of the equation x^2+2x-1=0, then prove that 4alpha^...

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  14. If one root of the quadratic equation (a-b)x^2+ax+1=0 is double the ot...

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  15. If the equation ax^(2) + bx + c = 0 and 2x^(2) + 3x + 4 = 0 have a co...

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  16. If the equation x^(3) + ax^(2) + b = 0, b ne 0 has a root of order 2, ...

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  17. If the roots of the equation x^(2) - bx + c = 0 are two consecutive in...

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  18. If the equations a x^2+b x+c=0 and x^3+3x^2+3x+2=0 have two common roo...

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  19. Let S denote the set of all real values of a for which the roots of th...

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  20. The sum of all real roots of the equation |x-2|^(2)+|x-2|-2=0 is

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