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Example

Solving {2x+y=7,  x2y=6}\{2x + y = 7,\; x - 2y = 6\} by Graphing

Solve the system {2x+y=7x2y=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)(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 x2y=6x - 2y = 6, use the intercept method. Setting y=0y = 0 gives x=6x = 6, so the x-intercept is (6,0)(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)=81=72(4) + (-1) = 8 - 1 = 7. Since 7=77 = 7 is true, the first equation is satisfied.
  • Second equation: 42(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).

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Updated 2026-04-24

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