Math Problem Statement

Solve the following system of equations by graphing: x + y = 2 and x - 2y = 8.

Solution

To solve the system of equations by graphing, we need to plot both equations on the same coordinate plane and find their point of intersection.

The system of equations is:

  1. x+y=2x + y = 2
  2. x2y=8x - 2y = 8

Step 1: Rewrite Each Equation in Slope-Intercept Form

Equation 1: x+y=2x + y = 2 Solve for yy: y=x+2y = -x + 2

Equation 2: x2y=8x - 2y = 8 Solve for yy: 2y=x+8    y=12x4-2y = -x + 8 \implies y = \frac{1}{2}x - 4

Step 2: Graph Both Equations

  1. Graph the first equation y=x+2y = -x + 2:

    • The y-intercept is 2 (point: (0,2)(0, 2)).
    • The slope is -1, so from the y-intercept, move down 1 unit and right 1 unit to plot the next point (point: (1,1)(1, 1)).
  2. Graph the second equation y=12x4y = \frac{1}{2}x - 4:

    • The y-intercept is -4 (point: (0,4)(0, -4)).
    • The slope is 12\frac{1}{2}, so from the y-intercept, move up 1 unit and right 2 units to plot the next point (point: (2,3)(2, -3)).

Step 3: Find the Point of Intersection

Now we need to find the point where these two lines intersect. Let's solve the system algebraically to find the intersection point:

Set the equations equal to each other: x+2=12x4-x + 2 = \frac{1}{2}x - 4

Combine like terms: 2x+4=x8-2x + 4 = x - 8

Simplify and solve for xx: 2xx=84    3x=12    x=4-2x - x = -8 - 4 \implies -3x = -12 \implies x = 4

Substitute x=4x = 4 back into one of the equations (e.g., y=x+2y = -x + 2): y=4+2=2y = -4 + 2 = -2

Solution:

The point of intersection is (4,2)(4, -2).

Therefore, the solution to the system of equations is: (4,2)\boxed{(4, -2)}

Would you like me to provide a graph to visualize this solution? Also, feel free to ask any of the following questions:

  1. How do you graph linear equations with different slopes?
  2. Can you explain more about the slope-intercept form of a line?
  3. How do you determine the solution of a system of equations by graphing?
  4. What happens if two lines are parallel when solving by graphing?
  5. How can I check if my solution is correct after solving graphically?

Tip: Always double-check your plotted points to ensure accuracy when solving systems by graphing!

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Math Problem Analysis

Mathematical Concepts

Algebra
Linear Equations
Systems of Equations

Formulas

Slope-intercept form y = mx + b

Theorems

Intersection point of two lines in a coordinate plane

Suitable Grade Level

Grades 8-10