Find y, if (begin{pmatrix}5 & -6 \2 & -7end{pmatrix}begin{pmatrix}x \ y end{pmatrix} = begin{pmatrix}7 \-11end{pmatrix})
- A.
8 - B.
5 - C.
3 - D.
2
Correct Answer: Option C
Explanation
(begin{pmatrix}5 & -6 \2 & -7end{pmatrix}begin{pmatrix} x \ y end{pmatrix} = begin{pmatrix}7 \-11end{pmatrix})
By matrices multiplication;
5x – 6y = 7 ……..(1)
2x – 7y = -11 ……(2)
2 x (1): 10x – 12y = 14 …….(3)
5 x (2): 10x – 35y = -55 ……(4)
(3) – (4): 23y = 69
y = 69/23 = 3
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