Math Problem Statement

Write an equation for the quadratic graphed below x -intercepts: (-2,0) and (1,0).
y -intercept: (0,3)

1 2 3 4 5 -1 -2 -3 -4 -5 1 2 3 4 5 -1 -2 -3 -4 -5

y

Solution

Given the information about the x-intercepts (2,0)(-2,0) and (1,0)(1,0) and the y-intercept (0,3)(0,3), we can construct the quadratic equation in the factored form as follows:

The general form of a quadratic equation with known x-intercepts is:

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

where x1x_1 and x2x_2 are the x-intercepts.

For the x-intercepts (2,0)(-2,0) and (1,0)(1,0), the equation becomes:

y=a(x+2)(x1)y = a(x + 2)(x - 1)

Now, use the y-intercept (0,3)(0,3) to find the value of aa. Substituting x=0x = 0 and y=3y = 3 into the equation:

3=a(0+2)(01)3 = a(0 + 2)(0 - 1)

3=a(2)(1)3 = a(2)(-1)

3=2a3 = -2a

Solving for aa:

a=32a = -\frac{3}{2}

Thus, the equation of the quadratic is:

y=32(x+2)(x1)y = -\frac{3}{2}(x + 2)(x - 1)

Expanding this equation:

y=32(x2+x2)y = -\frac{3}{2}(x^2 + x - 2)

y=32x232x+3y = -\frac{3}{2}x^2 - \frac{3}{2}x + 3

So, the quadratic equation is:

y=32x232x+3y = -\frac{3}{2}x^2 - \frac{3}{2}x + 3

Would you like further details or clarification on any steps?

Here are 5 related questions:

  1. How do you factor a quadratic equation from a graph?
  2. What is the significance of the y-intercept in a quadratic equation?
  3. Can you solve the quadratic equation using the quadratic formula instead?
  4. How do you determine the vertex of a quadratic equation from its graph?
  5. What role does the coefficient aa play in the shape of the parabola?

Tip: The sign of aa in a quadratic equation determines if the parabola opens upward or downward!

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Math Problem Analysis

Mathematical Concepts

Algebra
Quadratic Equations
Factored Form
Intercepts

Formulas

y = a(x - x1)(x - x2) for finding quadratic equation from intercepts
y = ax^2 + bx + c (expanded quadratic form)

Theorems

Intercept theorem: Roots of a quadratic equation correspond to x-intercepts
Factoring theorem: Quadratic equations can be represented in factored form

Suitable Grade Level

Grades 9-10