Explain How to Solve 5x² + 3x – 25 by Completing the Square: What Are the Solutions?

To solve the equation 5x² + 3x – 25 = 0 by completing the square, follow these steps:

  1. Divide the entire equation by 5:
    This simplifies the equation to: x² + (3/5)x – 5 = 0
  2. Rearrange the equation:
    Move the constant term to the other side:
    x² + (3/5)x = 5
  3. Complete the square:
    To do this, take half of the coefficient of x (which is 3/5), square it, and add this value to both sides of the equation.
    Half of (3/5) is (3/10) and squaring it gives (9/100).
    Now add (9/100) to both sides:
    x² + (3/5)x + (9/100) = 5 + (9/100)
  4. Simplify the equation:
    The left side can be factored as:
    (x + 3/10)² = 500/100 + 9/100 = 509/100
  5. Take the square root of both sides:
    x + 3/10 = ±√(509/100)
  6. Isolate x:
    x = -3/10 ± √(509)/10

Thus, the solutions to the equation are:

  • x = (-3 + √509) / 10
  • x = (-3 – √509) / 10

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