Math Problem Statement

Solve the system by graphing. 2x+3y=9; x-2y=8

Solution

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

1. Rewrite both equations in slope-intercept form (y = mx + b).

For the first equation:

2x+3y=92x + 3y = 9 Solve for yy: 3y=2x+93y = -2x + 9 y=23x+3y = -\frac{2}{3}x + 3

For the second equation:

x2y=8x - 2y = 8 Solve for yy: 2y=x+8-2y = -x + 8 y=12x4y = \frac{1}{2}x - 4

2. Graph both lines.

  • For the first line y=23x+3y = -\frac{2}{3}x + 3:

    • Slope: 23-\frac{2}{3}
    • y-intercept: 33 (the point (0,3)(0, 3))
  • For the second line y=12x4y = \frac{1}{2}x - 4:

    • Slope: 12\frac{1}{2}
    • y-intercept: 4-4 (the point (0,4)(0, -4))

3. Find the intersection point by graphing both lines and checking where they cross.

Plot both lines using their slopes and y-intercepts, and the point where the two lines intersect is the solution to the system.

4. Algebraic Solution for Intersection Point

Instead of graphing, you can solve algebraically:

  1. Set the two equations for yy equal to each other: 23x+3=12x4-\frac{2}{3}x + 3 = \frac{1}{2}x - 4

  2. Solve for xx: 23x12x=43-\frac{2}{3}x - \frac{1}{2}x = -4 - 3 46x36x=7-\frac{4}{6}x - \frac{3}{6}x = -7 76x=7-\frac{7}{6}x = -7 x=6x = 6

  3. Substitute x=6x = 6 into one of the original equations to find yy: Using y=12x4y = \frac{1}{2}x - 4: y=12(6)4=34=1y = \frac{1}{2}(6) - 4 = 3 - 4 = -1

Solution:

The lines intersect at (6,1)(6, -1), so the solution to the system is: x=6,y=1x = 6, \quad y = -1

Do you have any questions, or would you like further details?

5 Related Questions:

  1. How do you determine the slope of a line from its equation?
  2. What is the significance of the y-intercept in graphing a line?
  3. How can substitution or elimination methods be used instead of graphing to solve a system of equations?
  4. How do you convert between different forms of linear equations?
  5. What does it mean when two lines in a system are parallel?

Tip:

When graphing, always label the points where the lines cross the axes to ensure accuracy in locating the intersection.

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Math Problem Analysis

Mathematical Concepts

Algebra
Linear Equations
Graphing Systems of Equations

Formulas

Slope-intercept form y = mx + b
Equating two expressions to find intersection points

Theorems

Slope-intercept theorem
Intersection of two lines theorem

Suitable Grade Level

Grades 8-10