Worked examples
Two examples
Example 1
Solve the system: y = 2x and x + y = 9
- Put 2x in place of y in the second equation: x + 2x = 9.
- 3x = 9, so x = 3. Then y = 2 × 3 = 6.
Answer: (3, 6)
Example 2
Solve the system: y = x − 1 and 2x + y = 8
- 2x + (x − 1) = 8, so 3x − 1 = 8 and x = 3.
- y = 3 − 1 = 2.
Answer: (3, 2)
Where this is taught: Lines on the Grid, “Two equations at once: a system”
The drill
Ten problems
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.