Year 8 Substitution Worksheet — Level 3 — Practice Set 2 — Answers
Answer sheet with worked solutions for the Year 8 algebraic expressions worksheet.
Success TutoringWorksheetsAnswer sheetYear 8 · Mathematics · Algebraic ExpressionsYear 8 Substitution Worksheet — Level 3 — Practice Set 2 — Answers
Replace the letter with the number, then calculate. Use brackets for negative values.
1.If x = 5 and y = −2, find the value of 6x2 + 2y
Answer: 146
- 6 × (5)² + 2 × (−2)
- = 150 − 4 = 146
2.If x = −5 and y = −1, find the value of 8x2 + 3y
Answer: 197
- 8 × (−5)² + 3 × (−1)
- = 200 − 3 = 197
3.Find the value of −x − 8 when x = 1
Answer: −9
- −1 × 1 − 8
- = −1 − 8 = −9
4.If x = −4 and y = 4, find the value of x2 − 8y
Answer: −16
- 1 × (−4)² − 8 × (4)
- = 16 − 32 = −16
5.Find the value of x − 7 when x = −3
Answer: −10
- 1 × (−3) − 7
- = −3 − 7 = −10
6.If x = 9 and y = 2, find the value of 6x2 − 6y
Answer: 474
- 6 × (9)² − 6 × (2)
- = 486 − 12 = 474
7.Find the value of 2x + 8 when x = −1
Answer: 6
- 2 × (−1) + 8
- = −2 + 8 = 6
8.Find the value of 7x − 3 when x = 1
Answer: 4
- 7 × 1 − 3
- = 7 − 3 = 4
9.If x = 9 and y = 3, find the value of 4x2 + 8y
Answer: 348
- 4 × (9)² + 8 × (3)
- = 324 + 24 = 348
10.If x = −6 and y = −5, find the value of 2x2 − 9y
Answer: 117
- 2 × (−6)² − 9 × (−5)
- = 72 + 45 = 117
11.If x = −4 and y = 4, find the value of 8x2 + 8y
Answer: 160
- 8 × (−4)² + 8 × (4)
- = 128 + 32 = 160
12.Find the value of 9x − 6 when x = −3
Answer: −33
- 9 × (−3) − 6
- = −27 − 6 = −33
Marking tips
- Give credit for correct method even when the final answer slips — the working shows where the thinking went right.
- For open-ended tasks, use the success criteria as a checklist rather than looking for one "right" answer.
- Celebrate what went well first, then pick one thing to work on next.