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Consider the quadratic equation x2 = 4x - 5. How many solutions does the equation have?

1 Answer

4 votes

Answer:

  • no real solutions
  • 2 complex solutions

Explanation:

The equation can be rearranged to vertex form:

x^2 -4x = -5 . . . . . . . . . subtract 4x

x^2 -4x +4 = -5 +4 . . . . add 4

(x -2)^2 = -1 . . . . . . . . . show the left side as a square

x -2 = ±√-1 = ±i . . . . . . take the square root; the right side is imaginary

x = 2 ± i . . . . . . . . . . . . . add 2. These are the complex solutions.

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Comment on the question

Every 2nd degree polynomial equation has two solutions. They may be real, complex, or (real and) identical. That is, there may be 0, 1, or 2 real solutions. This equation has 0 real solutions, because they are both complex.

User Unbekant
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