Math Problem Statement

The graph of y = ax^2 + bx + c has a minimum at (5, -3) and passes through (4, 0). Find the values of a, b, and c.

Solution

The problem asks for the values of aa, bb, and cc in the quadratic equation y=ax2+bx+cy = ax^2 + bx + c, given that:

  • The minimum point of the parabola occurs at (5,3)(5, -3).
  • The graph passes through the point (4,0)(4, 0).

Step 1: Use the vertex form of a quadratic equation

Since the minimum (or vertex) is at (5,3)(5, -3), we can first express the equation of the parabola in vertex form: y=a(xh)2+ky = a(x - h)^2 + k where (h,k)(h, k) is the vertex of the parabola. Substituting h=5h = 5 and k=3k = -3, we get: y=a(x5)23y = a(x - 5)^2 - 3

Step 2: Use the point (4,0)(4, 0)

Now, we know that the parabola passes through (4,0)(4, 0). Substituting x=4x = 4 and y=0y = 0 into the equation: 0=a(45)230 = a(4 - 5)^2 - 3 0=a(1)230 = a(1)^2 - 3 0=a30 = a - 3 Thus, a=3a = 3.

Step 3: Rewrite the equation in standard form

Now that we know a=3a = 3, we can rewrite the equation in its expanded (standard) form: y=3(x5)23y = 3(x - 5)^2 - 3 Expanding this: y=3(x210x+25)3y = 3(x^2 - 10x + 25) - 3 y=3x230x+753y = 3x^2 - 30x + 75 - 3 y=3x230x+72y = 3x^2 - 30x + 72

Step 4: Identify aa, bb, and cc

From the expanded form, we have: a=3,b=30,c=72a = 3, \quad b = -30, \quad c = 72

Thus, the values of aa, bb, and cc are:

  • a=3a = 3
  • b=30b = -30
  • c=72c = 72

Would you like more details on any of these steps? Here are some related questions you might find useful:

  1. How do you find the vertex form of a quadratic equation?
  2. How can the axis of symmetry help in finding the vertex of a parabola?
  3. How does completing the square relate to converting from standard to vertex form?
  4. What are the key features of a parabola derived from the quadratic equation?
  5. Can you use the quadratic formula to verify the vertex?

Tip: Remember that the vertex of a parabola given by ax2+bx+cax^2 + bx + c occurs at x=b2ax = -\frac{b}{2a}. This can be a quick way to identify the x-coordinate of the minimum or maximum point.

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Math Problem Analysis

Mathematical Concepts

Algebra
Quadratic Equations

Formulas

y = ax^2 + bx + c
y = a(x - h)^2 + k

Theorems

Quadratic formula
Vertex form of a quadratic equation

Suitable Grade Level

Grades 9-11