Consider the general quadratic eqaution in standard form, ax^2 + bx + c = 0. Let a = 1 and the roots be r1 and r2. Expand (x - r1) (x - r2).

Question

Consider the general quadratic eqaution in standard form, ax^2 + bx + c = 0.  Let a = 1 and the roots be r1 and r2.  Expand (x - r1) (x - r2).
Write both algebraic expressions for and descriptions in words of b and c in terms of r1 and r2.

Damon · Answer

x^2 - r1 x - r2 x + r1 r2 b = -(r1+r2) c = r1 r2