Stage 11 · Quadratic Equations

11.5.2 Applying Vieta's Formulas Directly

11.5 The Relationship Between Roots and Coefficients (Vieta's Formulas)

Point 2 of 4

11.5.2 Applying Vieta's Formulas Directly

Core idea

Given one root, find the other — or use x₁+x₂ and x₁·x₂ as secret codes to answer without ever solving the equation.

Module goal. Read off the sum and product of the two roots without solving, then work backwards to build an equation from its roots and evaluate symmetric expressions.

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