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Question

What is the quadratic equation whose roots are 5 and 2

This question was previously asked in
RRB ALP 2018 CBT 2 Fitter Question Paper (21-Jan-2019) (Shift 3)
The correct answer is
$x^2 - 7x + 10 = 0$

To find the quadratic equation with given roots, we can use the relationship between the roots and the coefficients of a quadratic equation.

Finding the Quadratic Equation

Let the roots of the quadratic equation be \(\alpha\) and \(\beta\). The standard form of a quadratic equation with roots \(\alpha\) and \(\beta\) is given by:

\(x^2 - (\alpha + \beta)x + \alpha\beta = 0\)

Where:

  • \((\alpha + \beta)\) is the sum of the roots.
  • \(\alpha\beta\) is the product of the roots.

Step-by-Step Solution

  1. Identify the roots: The given roots are \(\alpha = 5\) and \(\beta = 2\).

  2. Calculate the sum of the roots:

    Sum \(= \alpha + \beta = 5 + 2 = 7\)

  3. Calculate the product of the roots:

    Product \(= \alpha \times \beta = 5 \times 2 = 10\)

  4. Substitute the sum and product into the standard equation format:

    \(x^2 - (\text{Sum})x + (\text{Product}) = 0\)

    \(x^2 - (7)x + 10 = 0\)

  5. Simplify the equation:

    \(x^2 - 7x + 10 = 0\)

  6. Match with the options: The derived equation \(x^2 - 7x + 10 = 0\) matches option 3.

Therefore, the quadratic equation whose roots are 5 and 2 is \(x^2 - 7x + 10 = 0\).

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Similar Questions

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  3. Solve for x in \(12x^2 + 45x = 0\)
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Important Questions from Quadratic equation

  1. Find the minimum value of 2x² – 5x – 3 and also find x.

  2. A quadratic equation $x^2 + 3x + k = 0$ has a discriminant equal to 9. What is the value of k?

  3. Reduce the equation $x^4 - 13x^2 + 36 = 0$ into a quadratic equation and find the roots of the reduced quadratic equation.
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  5. The nature of the roots of the quadratic equation $3x^{2} – 5x + 2 = 0$ is:
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