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Sea A ∈ R n × n {\displaystyle A\in \mathbb {R} ^{n\times n}} una matriz diagonal, b ∈ R n {\displaystyle b\in \mathbb {R} ^{n}} . ( ( ∃ i ∈ 1 , . . . , n ) / ( A i , i = 0 & b i ≠ 0 ) ⟹ {\displaystyle ((\exists i\in 1,...,n)\ /\ (A_{i,i}=0\&b_{i}\neq 0)\Longrightarrow } no existe solucion. ( ( ∃ i ∈ 1 , . . . , n ) / ( A i , i = 0 & b i = 0 ) ⟹ {\displaystyle ((\exists i\in 1,...,n)\ /\ (A_{i,i}=0\&b_{i}=0)\Longrightarrow } existen infinitas soluciones. ( ( ∀ i ∈ 1 , . . . , n ) A i , i ≠ 0 ) ⟹ {\displaystyle ((\forall i\in 1,...,n)\ A_{i,i}\neq 0)\Longrightarrow } la solución del sistema es x {\displaystyle x} tal que ( ∀ i ∈ 1 , . . . , n ) x i = b i A i , i {\displaystyle (\forall i\in 1,...,n)\ x_{i}={\frac {b_{i}}{A_{i,i}}}} .