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Complex roots occur when a polynomial equation has no real solutions — the discriminant is negative. The roots come in conjugate pairs: a + bi and a − bi, where i = √(−1).

공식

For ax² + bx + c = 0: x = (−b ± √(b²−4ac))/(2a); √(negative) = i√(|negative|)
a, b, c
quadratic coefficients
Δ
discriminant (b²−4ac) — determines if roots are real or complex
i
imaginary unit — where i² = −1

단계별 가이드

  1. 1For ax² + bx + c = 0: roots = (−b ± √(b²−4ac)) / 2a
  2. 2When b²−4ac < 0: roots are complex
  3. 3√(negative) = i × √(|negative|)
  4. 4Complex roots always appear as conjugate pairs

풀어진 예시

입력
x² + 4 = 0
결과
x = ±2i
입력
x² − 2x + 5 = 0
결과
x = 1 ± 2i

자주 묻는 질문

What is the complex conjugate of a root?

If 3 + 2i is a root, then 3 − 2i is its conjugate. They always appear in pairs for real polynomials.

When do complex roots occur?

When the discriminant b²−4ac is negative. This means the parabola doesn't cross the x-axis.

Can I visualize complex roots on a number line?

No, complex roots require a 2D plane (complex plane): real part on x-axis, imaginary part on y-axis.

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