| j * j = i * j0 * j0, 0 < i, j ≠ 0 ∨ j0 ≠ 0 ⊦ ∃ i0. i = i0 * i0, 0 < j ∧ 0 < j0 |
j * j = i * j0 * j0, 0 < i, j < 0, j ≠ 0 ∨ j0 ≠ 0 ⊦ ∃ i0. i = i0 * i0, 0 < j ∧ 0 < j0
j * j = i * j0 * j0, 0 < i, j ≠ 0 ∨ j0 ≠ 0 ⊦ j < 0, ∃ i0. i = i0 * i0, 0 < j ∧ 0 < j0
Used formulas: j < 0