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Test: Quadratic trinomials and factorisation

This test focuses on transforming and factorising quadratic trinomials. Tasks cover expansion, completing the square, vertex form and selecting an appropriate algebraic method for a given expression.

Question qty: 10
Duration in minutes: 20
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Time left: 00:00:00

Sample questions

  • Find k so that x² + kx + c equals (x + a)².
  • Factorise x² + sx + p.
  • What does a positive discriminant of a quadratic trinomial mean?
  • When factoring using roots x₁ and x₂, why is the form (x − x₁)(x − x₂) used?
  • Expand (x − (a))(x − (b)).
  • For y = (x − (m))² + (n), give the vertex.
  • Write x² + a2x + a_sq as a perfect square.
  • Factorise x² − sx + p.

Quadratic trinomials and factorisation

A quadratic trinomial ax² + bx + c can be factored using the roots of its corresponding equation: ax² + bx + c = a(x − x₁)(x − x₂). A repeated root gives a(x − x₀)².

Vieta formulas

The roots satisfy x₁ + x₂ = −b/a and x₁x₂ = c/a. These relationships help select factors and check roots. Take out a common factor first; if the discriminant is negative, the trinomial has no factorisation into real linear factors.