Question

If $\left(\begin{array}{cc}y+2x& 5\\ -x& 3\end{array}\right)=\left(\begin{array}{cc}7& 5\\ -2& 3\end{array}\right)$, find the value of $y$.

Answer 1

We have,

$\left(\begin{array}{cc}y+2x& 5\\ -x& 3\end{array}\right)=\left(\begin{array}{cc}7& 5\\ -2& 3\end{array}\right)$

On comparing both sides, we get

$y+2x=7$ and $x=2$

So,

$y+2\times 2=7$

$y+4=7$

$y=3$

Hence, this is the answer.