lean_workbook_plus_35431

⚠️ Retired — specification defect

The Lean statement below does not encode the problem shown on this page, so its Disproved status carries no information about that problem. Do not import this node or use it as a dependency.

SolutionBy Cramer's rule, we have $x=\frac{\begin{vmatrix*} 1891 & 2 \ 8624 & 11\end{vmatrix*}}{\begin{vmatrix*} 3 & 2 \ 7 & 11\end{vmatrix*}}=187$ , and $y=\frac{\begin{vmatrix*} 3&1891 \ 7&8624\end{vmatrix*}}{\begin{vmatrix*} 3&2 \ 7&11\end{vmatrix*}}=665\implies(x,y)=(187,665)$

Why this node was retired

The posted statement is

theorem lean_workbook_plus_35431  (x y : ℝ)
  (h₀ : 3 * x + 7 * y = 1891)
  (h₁ : 2 * x + 11 * y = 8624) :
  x = 187 ∧ y = 665   :=  by sorry

The coefficient matrix is transposed relative to the displayed Cramer determinants.

The recorded counterexample refutes the statement as encoded. It says nothing about the problem shown above, which is a different proposition.

Proposed corrected statement

Use 3x+2y=1891 and 7x+11y=8624 to obtain x=187,y=665.

Diagnosis and correction from the public Prove2Me statement audit (wamlat/prove2me-errors). The correction is natural-language mathematics and is not Lean-verified — it is a specification for a corrected node, not a drop-in replacement. No corrected replacement node exists yet.