Math Problem Statement

Write an equation of the parabola that passes through the point (-6,9) and has x-intercepts -2 and 3

Solution

To find the equation of a parabola that passes through the point (6,9)(-6, 9) and has xx-intercepts at 2-2 and 33, we can use the fact that the parabola's equation in factored form is:

y=a(xx1)(xx2)y = a(x - x_1)(x - x_2)

where x1x_1 and x2x_2 are the xx-intercepts. Since the xx-intercepts are 2-2 and 33, we can substitute them into the equation:

y=a(x+2)(x3)y = a(x + 2)(x - 3)

Now, we need to determine the value of aa using the point (6,9)(-6, 9), which lies on the parabola. Substitute x=6x = -6 and y=9y = 9 into the equation:

9=a(6+2)(63)9 = a(-6 + 2)(-6 - 3)

Simplify within the parentheses:

9=a(4)(9)9 = a(-4)(-9)

9=36a9 = 36a

Now, solve for aa:

a=936=14a = \frac{9}{36} = \frac{1}{4}

Thus, the equation of the parabola is:

y=14(x+2)(x3)y = \frac{1}{4}(x + 2)(x - 3)

We can expand this if you want it in standard form:

  1. Distribute (x+2)(x3)(x + 2)(x - 3): y=14(x23x+2x6)y = \frac{1}{4}(x^2 - 3x + 2x - 6) y=14(x2x6)y = \frac{1}{4}(x^2 - x - 6)

  2. Distribute 14\frac{1}{4}: y=14x214x32y = \frac{1}{4}x^2 - \frac{1}{4}x - \frac{3}{2}

So, the equation in standard form is:

y=14x214x32y = \frac{1}{4}x^2 - \frac{1}{4}x - \frac{3}{2}

Would you like further details or have any questions?

Related Questions

  1. How would the equation change if the point given was (6,9)(-6, -9) instead?
  2. Can we determine the vertex of this parabola from the equation?
  3. How can we find the axis of symmetry for this parabola?
  4. What are the steps to convert this equation into vertex form?
  5. How does changing the value of aa affect the shape of the parabola?

Tip: Factored form is helpful for quickly identifying the roots of a parabola and setting up an equation based on those roots.

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Math Problem Analysis

Mathematical Concepts

Algebra
Quadratic Equations
Factored Form of Parabolas

Formulas

Factored form of a quadratic equation: y = a(x - x1)(x - x2)
Standard form of a quadratic equation: y = ax^2 + bx + c

Theorems

Root theorem for parabolas
Properties of parabolas passing through a given point

Suitable Grade Level

Grades 9-10