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 to find the values of aa, bb, and cc in the quadratic equation:

y=ax2+bx+cy = ax^2 + bx + c

given the following conditions:

  1. The graph has a minimum at the point (5,3)(5, -3).
  2. The graph passes through the point (4,0)(4, 0).

Step 1: Use the vertex form of a parabola

The minimum point (5,3)(5, -3) tells us that the vertex of the parabola is at x=5x = 5. The vertex form of a quadratic function is:

y=a(xh)2+ky = a(x - h)^2 + k

where (h,k)(h, k) is the vertex. In this case, h=5h = 5 and k=3k = -3, so we can write the equation as:

y=a(x5)23y = a(x - 5)^2 - 3

Step 2: Use the point (4,0)(4, 0) to find aa

Now, substitute x=4x = 4 and y=0y = 0 (the point (4,0)(4, 0)) into the equation:

0=a(45)230 = a(4 - 5)^2 - 3 0=a(1)230 = a(1)^2 - 3 a3=0a - 3 = 0 a=3a = 3

Step 3: Write the equation in standard form

Now that we know a=3a = 3, we can substitute this value back into the vertex form:

y=3(x5)23y = 3(x - 5)^2 - 3

Expand the equation:

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

Thus, the quadratic equation is:

y=3x230x+72y = 3x^2 - 30x + 72

Conclusion

The values of aa, bb, and cc are:

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

Would you like any further details or explanations?

Related Questions:

  1. How do we know the point (5,3)(5, -3) represents a minimum for this parabola?
  2. What other forms of quadratic equations are useful for solving vertex problems?
  3. How can you verify if a point lies on the graph of a quadratic function?
  4. What is the significance of the discriminant in quadratic equations?
  5. How can we find the axis of symmetry of any quadratic function?

Tip:

When given the vertex of a quadratic function, using the vertex form of the equation can make solving much simpler!

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Math Problem Analysis

Mathematical Concepts

Algebra
Quadratic Equations
Vertex Form
Graphing Parabolas

Formulas

y = ax^2 + bx + c (Standard form of a quadratic equation)
y = a(x - h)^2 + k (Vertex form of a quadratic equation)

Theorems

Vertex of a parabola is the minimum or maximum point
The derivative of a quadratic function gives its minimum/maximum

Suitable Grade Level

Grades 9-12