Question

socorro preciso de ajuda
determine x e y para que as matrizes A e B sejam iguais
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Answer 1

$\Large\boxed{\begin{array}{l}\sf A=\begin{bmatrix}\sf4+y&\sf3\\\!\sf3x&\!\sf-1\end{bmatrix}\\\\\sf B=\begin{bmatrix}\sf7&\sf\,\,\,3\\\sf9&\sf-1\end{bmatrix}\\\\\sf A=B\iff\begin{bmatrix}\sf4+y&\,\sf3\\\sf3x&\!\!\sf-1\end{bmatrix}=\begin{bmatrix}\sf7&\sf3\\\sf9&\sf-1\end{bmatrix}\\\\\begin{cases}\sf 4+y=7\\\sf3x=9\end{cases}\end{array}}$

$\Large\boxed{\begin{array}{l}\sf 4+y=7\\\sf y=7-4\\\sf y=3\\\sf 3x=9\\\sf x=\dfrac{9}{3}\\\\\sf x=3\end{array}}$