Math Problem Statement

The parabola of the form y = ax^2 + bx + c which passes through the three points (0, -2), (1, -1), and (-1, 1) is:

Solution

To determine which parabola y=ax2+bx+cy = ax^2 + bx + c passes through the points (0,2)(0, -2), (1,1)(1, -1), and (1,1)(-1, 1), we need to substitute these points into the general form of the parabola and solve for aa, bb, and cc. Let's solve this step-by-step:


Step 1: Substituting Points into the General Form

For a parabola y=ax2+bx+cy = ax^2 + bx + c, substitute each point:

  1. Point (0,2)(0, -2): 2=a(0)2+b(0)+c    c=2-2 = a(0)^2 + b(0) + c \implies c = -2

  2. Point (1,1)(1, -1): 1=a(1)2+b(1)+c    1=a+b2-1 = a(1)^2 + b(1) + c \implies -1 = a + b - 2 a + b = 1 \tag{1}

  3. Point (1,1)(-1, 1): 1=a(1)2+b(1)+c    1=ab21 = a(-1)^2 + b(-1) + c \implies 1 = a - b - 2 a - b = 3 \tag{2}


Step 2: Solving the System of Equations

We now solve the system of equations:

  1. a+b=1a + b = 1
  2. ab=3a - b = 3

Add the two equations: (a+b)+(ab)=1+3    2a=4    a=2(a + b) + (a - b) = 1 + 3 \implies 2a = 4 \implies a = 2

Substitute a=2a = 2 into a+b=1a + b = 1: 2+b=1    b=12 + b = 1 \implies b = -1

From earlier, c=2c = -2.


Step 3: Writing the Parabola Equation

The equation of the parabola is: y=2x2x2y = 2x^2 - x - 2


Step 4: Comparing with the Options

From the options provided, the equation matches (c) y=2x2x2y = 2x^2 - x - 2.


Final Answer: (c)

Would you like further clarification or more detailed steps? Here are five related questions for you to consider:

  1. How do you determine the general equation of a parabola given points?
  2. What happens if more than three points are given for a quadratic equation?
  3. How can you verify the solution graphically?
  4. How do different coefficients aa, bb, and cc affect the shape and position of the parabola?
  5. Can you derive a quadratic equation if only two points are provided?

Tip: Always check your solution by substituting the points into the final equation to ensure consistency!

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Math Problem Analysis

Mathematical Concepts

Algebra
Quadratic Functions
System of Linear Equations

Formulas

General form of a parabola: y = ax^2 + bx + c
System of linear equations for solving coefficients

Theorems

Concept of unique solutions for a quadratic equation passing through three points

Suitable Grade Level

Grades 9-11