Given roots alpha, beta of + bx + c = 0, find equations with roots:
Roots , : Sum = (alpha+beta)^2 - 2alphabeta = / - 2c/a. Product = (alphabeta)^2 = /. Equation: - ()x + = 0.
Roots 1/alpha, 1/beta: Replace x by 1/x in original: a/ + b/x + c = 0 → + 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: a^2 + b + c = 0 → + bkx + = 0.
Roots -alpha, -beta: Replace x by -x: - bx + c = 0 (negate middle coefficient).