Let’s solve each trinomial by factoring.
We’re looking for two numbers that:
- Multiply to give the
last number (constant term)
- Add up to give the
middle number (coefficient of x)
Then we write the answer as:
(x + first number)(x + second number)
---
1. $ x^2 + 18x + 80 $
Find two numbers that multiply to 80 and add to 18.
Try:
→ 8 × 10 = 80, and 8 + 10 = 18 →
✔
Answer:
(x + 8)(x + 10)
---
2. $ x^2 + 13x + 36 $
Multiply to 36, add to 13.
Try:
→ 4 × 9 = 36, 4 + 9 = 13 →
✔
Answer:
(x + 4)(x + 9)
---
3. $ x^2 + 12x + 20 $
Multiply to 20, add to 12.
Try:
→ 2 × 10 = 20, 2 + 10 = 12 →
✔
Answer:
(x + 2)(x + 10)
---
4. $ x^2 + 15x + 56 $
Multiply to 56, add to 15.
Try:
→ 7 × 8 = 56, 7 + 8 = 15 →
✔
Answer:
(x + 7)(x + 8)
---
5. $ x^2 + 7x + 12 $
Multiply to 12, add to 7.
Try:
→ 3 × 4 = 12, 3 + 4 = 7 →
✔
Answer:
(x + 3)(x + 4)
---
6. $ x^2 + 11x + 24 $
Multiply to 24, add to 11.
Try:
→ 3 × 8 = 24, 3 + 8 = 11 →
✔
Answer:
(x + 3)(x + 8)
---
7. $ x^2 + 9x + 20 $
Multiply to 20, add to 9.
Try:
→ 4 × 5 = 20, 4 + 5 = 9 →
✔
Answer:
(x + 4)(x + 5)
---
8. $ x^2 + 16x + 64 $
Multiply to 64, add to 16.
Try:
→ 8 × 8 = 64, 8 + 8 = 16 →
✔
Answer:
(x + 8)(x + 8) or
(x + 8)²
---
9. $ x^2 + 11x + 18 $
Multiply to 18, add to 11.
Try:
→ 2 × 9 = 18, 2 + 9 = 11 →
✔
Answer:
(x + 2)(x + 9)
---
10. $ x^2 + 11x + 30 $
Multiply to 30, add to 11.
Try:
→ 5 × 6 = 30, 5 + 6 = 11 →
✔
Answer:
(x + 5)(x + 6)
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Final Answer:
(x + 8)(x + 10)
(x + 4)(x + 9)
(x + 2)(x + 10)
(x + 7)(x + 8)
(x + 3)(x + 4)
(x + 3)(x + 8)
(x + 4)(x + 5)
(x + 8)²
(x + 2)(x + 9)
(x + 5)(x + 6)
Parent Tip: Review the logic above to help your child master the concept of worksheet factoring trinomials answers.