Learn Before
Example

Solving {2x+y=7,;x−2y=6}\{2x + y = 7,; x - 2y = 6\} by Graphing

Solve the system {2x+y=7x−2y=6\left\{\begin{array}{l} 2x + y = 7 x - 2y = 6 \end{array}\right. using the graphing method.

Step 1 — Graph the first equation. Rewrite 2x+y=72x + y = 7 in slope-intercept form by isolating yy:

y=−2x+7y = -2x + 7

The slope is m=−2m = -2 and the y-intercept is (0, 7). Plot the y-intercept and use the slope to find additional points, then draw the line.

Step 2 — Graph the second equation on the same grid. For x−2y=6x - 2y = 6, use the intercept method. Setting y=0y = 0 gives x=6x = 6, so the x-intercept is (6, 0). Setting x=0x = 0 gives −2y=6-2y = 6, so y=−3y = -3 and the y-intercept is (0,−3)(0, -3). Plot these intercepts and draw the line.

Step 3 — Determine the relationship between the lines. The two lines intersect at a single point.

Step 4 — Identify and verify the solution. The lines intersect at (4,−1)(4, -1). Check this ordered pair in both equations:

  • First equation: 2(4)+(−1)=8−1=72(4) + (-1) = 8 - 1 = 7. Since 7=77 = 7 is true, the first equation is satisfied.
  • Second equation: 4−2(−1)=4+2=64 - 2(-1) = 4 + 2 = 6. Since 6=66 = 6 is true, the second equation is also satisfied.

Because (4,−1)(4, -1) makes both equations true, the solution of the system is (4,−1)(4, -1).

Image 0

0

1

Updated 2026-04-24

Contributors are:

Who are from:

Tags

OpenStax

Elementary Algebra @ OpenStax

Ch.5 Systems of Linear Equations - Elementary Algebra @ OpenStax

Algebra

Math

Prealgebra

Intermediate Algebra @ OpenStax

Ch.4 Systems of Linear Equations - Intermediate Algebra @ OpenStax

Related
Learn After