Math Problem Statement

Solve the system of equations by graphing. First graph the equations, and then fill in the solutions. y= 1/2(x–3)^2 +1 y=– x+8

Solution

To solve the system of equations by graphing, follow these steps:

Step 1: Identify the Equations

We are given:

  1. y=12(x3)2+1y = \frac{1}{2}(x - 3)^2 + 1 → This is a parabola that opens upward with its vertex at (3,1)(3,1).
  2. y=x+8y = -x + 8 → This is a straight line with a slope of -1 and a y-intercept at (0,8)(0,8).

Step 2: Graph Each Equation

  1. Parabola y=12(x3)2+1y = \frac{1}{2}(x - 3)^2 + 1

    • Vertex: (3,1)(3,1)
    • Direction: Opens upward because the coefficient 12\frac{1}{2} is positive.
    • Additional Points:
      • At x=1x = 1, y=12(13)2+1=12(4)+1=3y = \frac{1}{2}(1-3)^2 +1 = \frac{1}{2}(4) +1 = 3 → Point (1,3)(1,3)
      • At x=5x = 5, y=12(53)2+1=12(4)+1=3y = \frac{1}{2}(5-3)^2 +1 = \frac{1}{2}(4) +1 = 3 → Point (5,3)(5,3)
  2. Line y=x+8y = -x + 8

    • Y-intercept: (0,8)(0,8)
    • Slope: -1 (moves down 1 unit for every 1 unit to the right)
    • Additional Points:
      • At x=1x = 1, y=1+8=7y = -1 + 8 = 7 → Point (1,7)(1,7)
      • At x=2x = 2, y=2+8=6y = -2 + 8 = 6 → Point (2,6)(2,6)

Step 3: Find Intersection Points

By solving algebraically, set both equations equal to each other:

12(x3)2+1=x+8\frac{1}{2}(x - 3)^2 + 1 = -x + 8

  1. Subtract 1 from both sides:

12(x3)2=x+7\frac{1}{2}(x - 3)^2 = -x + 7

  1. Multiply everything by 2 to eliminate the fraction:

(x3)2=2x+14(x - 3)^2 = -2x + 14

  1. Expand:

x26x+9=2x+14x^2 - 6x + 9 = -2x + 14

  1. Move everything to one side:

x24x5=0x^2 - 4x - 5 = 0

  1. Factor:

(x5)(x+1)=0(x - 5)(x + 1) = 0

  1. Solve for xx:

x=5orx=1x = 5 \quad \text{or} \quad x = -1

  1. Find corresponding yy-values using y=x+8y = -x + 8:

    • If x=5x = 5, then y=5+8=3y = -5 + 8 = 3 → Point (5,3)(5,3).
    • If x=1x = -1, then y=(1)+8=9y = -(-1) + 8 = 9 → Point (1,9)(-1,9).

Final Answer:

The system of equations intersects at (5,3) and (-1,9).


Would you like a graph of the solution? Also, do you need a step-by-step explanation of any part?

Related Questions:

  1. How do you determine the vertex of a parabola?
  2. What are the different ways to solve a system of equations?
  3. How do you factor quadratic equations?
  4. What are the key properties of a parabola?
  5. How do you determine the slope and y-intercept of a linear equation?

Tip:

When solving systems of equations graphically, always check for symmetry in parabolas and use a table of values to ensure accurate plotting.

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Math Problem Analysis

Mathematical Concepts

Graphing Systems of Equations
Quadratic Functions
Linear Equations
Intersection of Graphs

Formulas

Quadratic Equation: y = a(x-h)^2 + k (Vertex Form)
Linear Equation: y = mx + b (Slope-Intercept Form)

Theorems

Intersection Points of a Parabola and a Line

Suitable Grade Level

Grades 9-11