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Question

If sum and product of the roots of a quadratic equation are $(4-3\sqrt{2})$ and -28, respectively, then find the quadratic equation.

The correct answer is
$x^2-(4-3\sqrt{2})x-28=0$

Finding the Quadratic Equation from Sum and Product of Roots

The problem asks us to find a quadratic equation given the sum and product of its roots.

Standard Form of a Quadratic Equation

A quadratic equation can be generally represented in the form:

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

Let the sum of the roots be denoted by $S$ and the product of the roots be denoted by $P$. The equation is then:

$$x^2 - Sx + P = 0$$

Given Values

From the question, we have:

  • Sum of the roots, $S = (4-3\sqrt{2})$
  • Product of the roots, $P = -28$

Constructing the Equation

Now, we substitute these values into the standard form:

$$x^2 - (4-3\sqrt{2})x + (-28) = 0$$

Simplifying the equation, we get:

$$x^2 - (4-3\sqrt{2})x - 28 = 0$$

Matching with Options

Comparing this result with the given options:

  • Option 1: $x^2-(4+3\sqrt{2})x+28=0$
  • Option 2: $x^2+(4+3\sqrt{2})x+28=0$
  • Option 3: $x^2+(4-3\sqrt{2})x-28=0$
  • Option 4: $x^2-(4-3\sqrt{2})x-28=0$

Our derived equation matches Option 4.

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Important Questions from Quadratic equation

  1. What number should be subtracted from x3−4x2−8x+11 to make the number divisible by (x+2)?

  2. Find the value of K if the quadratic equations $2x^2 + Kx + 8 = 0$ and $3x^2 + 4x + 12 = 0$ have both roots common.
  3. If the quadratic equations $4x^2 + bx + 3 = 0$ and $8x^2 + 4x + c = 0$ have both the roots common, find the values for b and c, respectively.
  4. Determine the nature of the roots of the quadratic equation $3x^2 + 2x + 5 = 0$.
  5. Find roots of $5m^2 + 18m + 16 = 0$
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