Final answer:
1. ∃x∀y(xy = 0) is false. 2. ∃x (x² = -1) is false. 3. ∃x∀y≠0(xy = 1) is true. 4. ∀xSy((x + y = 2) ∧ (2x - y = 1)) is true. 5. ∀x #0∃y(xy = 1) is true. 6. ∃x(x² = 2) is true. 7. ∀x∃y(x2 = y) is false. 8. ∀x∃y (x = y²) is false. 9. ∃x∃y (x + y ≠ y + x) is true. 10. ∀x∃zty(z = (x+y)/2) is true. 11. ∃x∃y ((x + 2y = 2)^(2x + 4y = 5)) is false. 12. ∀x∃y(x + y = 1) is false.
Step-by-step explanation:
- ∃x∀y(xy = 0) - False
- ∃x (x² = -1) - False
- ∃x∀y≠0(xy = 1) - True
- ∀xSy((x + y = 2) ∧ (2x - y = 1)) - True
- ∀x #0∃y(xy = 1) - True
- ∃x(x² = 2) - True
- ∀x∃y(x2 = y) - False
- ∀x∃y (x = y²) - False
- ∃x∃y (x + y ≠ y + x) - True
- ∀x∃zty(z = (x+y)/2) - True
- ∃x∃y ((x + 2y = 2)^(2x + 4y = 5)) - False
- ∀x∃y(x + y = 1) - False