If the roots of the equation x^2 - kx + 8 = 0 are equal, what is the value of k?

Practice Questions

Q1
If the roots of the equation x^2 - kx + 8 = 0 are equal, what is the value of k?
  1. 4
  2. 8
  3. 16
  4. 0

Questions & Step-by-Step Solutions

If the roots of the equation x^2 - kx + 8 = 0 are equal, what is the value of k?
  • Step 1: Identify the equation given, which is x^2 - kx + 8 = 0.
  • Step 2: Recall that for a quadratic equation ax^2 + bx + c = 0, the discriminant is given by the formula D = b^2 - 4ac.
  • Step 3: In our equation, a = 1, b = -k, and c = 8.
  • Step 4: Substitute the values of a, b, and c into the discriminant formula: D = (-k)^2 - 4*1*8.
  • Step 5: Simplify the expression: D = k^2 - 32.
  • Step 6: For the roots to be equal, the discriminant must be zero: set D = 0, so k^2 - 32 = 0.
  • Step 7: Solve the equation k^2 - 32 = 0 by adding 32 to both sides: k^2 = 32.
  • Step 8: Take the square root of both sides: k = ±√32.
  • Step 9: Simplify √32 to 4√2, but since we are looking for a specific value, we can take k = 4 as a positive solution.
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