Find X if 2X + [-1, 3; 2, 2] = [1, 7; 6, 0].

Question 38

MediumOriginal question

Find $X$ if $2X + \begin{bmatrix}-1 & 3 \\ 2 & 2\end{bmatrix} = \begin{bmatrix}1 & 7 \\ 6 & 0\end{bmatrix}$ .

\begin{bmatrix}1 & 2 \\ 2 & -1\end{bmatrix}

Correct answerYour answer

\begin{bmatrix}0 & 5 \\ 4 & 1\end{bmatrix}

Correct answerYour answer

\begin{bmatrix}2 & 4 \\ 4 & -2\end{bmatrix}

Correct answerYour answer

\begin{bmatrix}-1 & -2 \\ -2 & 1\end{bmatrix}

Correct answerYour answer

Show the answer and explanation

CorrectNot quiteAnswer A

Correct answer: A

Subtract first: $2X = \begin{bmatrix}1 & 7 \\ 6 & 0\end{bmatrix} - \begin{bmatrix}-1 & 3 \\ 2 & 2\end{bmatrix} = \begin{bmatrix}2 & 4 \\ 4 & -2\end{bmatrix}$ .
Then halve every element: $X = \begin{bmatrix}1 & 2 \\ 2 & -1\end{bmatrix}$ .

Worth noting

$\begin{bmatrix}2 & 4 \\ 4 & -2\end{bmatrix}$ is $2X$ , not $X$ .

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