How to Write Quadratic Equations in Vertex Form and Standard Form

Learn how to write quadratic equations using vertex form from a vertex, or standard form from 3 points. Let’s get started! 🚀

How to Write Quadratic Equations in Vertex Form and Standard Form - introduction visual

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Quadratic equations with vertex form y = a(x - h)² + k and general form y = ax² + bx + c, labelled as methods for forming quadratic equations.Forming a quadratic equation using vertex form with equation y = -2(x - 2)² + 3, where the vertex is (2,3) and the curve passes through (3,1).Forming quadratic equations using the general form y = 2x² - x + 3, solving coefficients with three given points: (0,3), (1,4), and (2,9).Solving the classic tunnel problem. The parabola equation is y = -5/9 · x² + 5 and the vertex is at (0,5). When x = 1, the truck can pass through.

🛎️ Forms of Quadratic Equations

  • Quadratics can be written in vertex form or general form.
  • Use vertex form when you know the vertex, and general form when you know points on the parabola.

🛎️ Using the Vertex Form

  • If the vertex is (2, 3), start with y = a(x − 2)² + 3.
  • Substitute the point (3, 1) to make an equation and find the value of a.

🛎️ Using the General Form

  • Substitute three known points to make three equations.
  • Solve the equations together using substitution or elimination to find a, b, and c.

🛎️ Applying Quadratics to a Real-Life Situation

  • The equation y = −5/9 x² + 5 models the shape of a bridge.
  • Substituting x = 1 shows the height is above 4 m, so the truck can drive through.

Practice Questions

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Interactive Activity

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