Worked examples
Two examples
Example 1
Solve the system: x + y = 10 and x − y = 4
- The y terms are opposites, so add the equations: 2x = 14, x = 7.
- Back into the first: 7 + y = 10, so y = 3.
Answer: (7, 3)
Example 2
Solve the system: 2x + 3y = 13 and 2x − y = 1
- The x terms are the same, so subtract the second from the first: 4y = 12, y = 3.
- Back into the first: 2x + 9 = 13, so x = 2.
Answer: (2, 3)
Where this is taught: Lines on the Grid, “Two equations at once: a system”
The drill
Ten problems
This drill also has challenge problems. They use the same skill, set up the way the GED test sometimes sets up a problem, so that it looks new at first.
How many:
Type each answer as a point, like (3, -2). Then press Check my answers at the bottom.Write each answer as a point, like (3, −2). The answer key, with the reasoning, is on the last page.