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Question

For what values of k will the equation $x^2 + kx + 361 = 0$ have equal roots?

The correct answer is
±38

Quadratic Equation Analysis

The given equation is a quadratic equation of the form $ax^2 + bx + c = 0$. In this case, the equation is $x^2 + kx + 361 = 0$. Comparing the terms, we have:

  • $a = 1$
  • $b = k$
  • $c = 361$

Condition for Equal Roots

A quadratic equation has equal roots if its discriminant ($\Delta$) is equal to zero. The discriminant is calculated using the formula:

$ \Delta = b^2 - 4ac $

For equal roots, we set $\Delta = 0$:

$ b^2 - 4ac = 0 $

Solving for k

Substitute the values of $a$, $b$, and $c$ into the condition:

$ k^2 - 4(1)(361) = 0 $

Simplify the equation:

$ k^2 - 1444 = 0 $

Isolate $k^2$:

$ k^2 = 1444 $

Take the square root of both sides to find the values of $k$:

$ k = \pm \sqrt{1444} $

Calculate the square root:

$ \sqrt{1444} = 38 $

Therefore, the values of $k$ for which the equation will have equal roots are:

$ k = \pm 38 $

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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 sum and product of the roots of a quadratic equation are $(4-3\sqrt{2})$ and -28, respectively, then find the quadratic equation.
  4. 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.
  5. Determine the nature of the roots of the quadratic equation $3x^2 + 2x + 5 = 0$.
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