Part of ALG-05 — Quadratic Equations

Forming New Equations from Given Roots

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Given roots alpha, beta of ax2ax^2 + bx + c = 0, find equations with roots:

Roots alpha2alpha^2, beta2beta^2: Sum = (alpha+beta)^2 - 2alphabeta = b2b^2/a2a^2 - 2c/a. Product = (alphabeta)^2 = c2c^2/a2a^2. Equation: a2a^2x2x^2 - (b22acb^{2-2ac})x + c2c^2 = 0.

Roots 1/alpha, 1/beta: Replace x by 1/x in original: a/x2x^2 + b/x + c = 0 → cx2cx^2 + bx + a = 0 (reverse coefficients).

Roots alpha+k, beta+k: Replace x by x-k in original: a(x-k)^2 + b(x-k) + c = 0.

Roots kalpha, kbeta: Replace x by x/k in original: axk\frac{x}{k}^2 + bxk\frac{x}{k} + c = 0 → ax2ax^2 + bkx + ck2ck^2 = 0.

Roots -alpha, -beta: Replace x by -x: ax2ax^2 - bx + c = 0 (negate middle coefficient).

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