Question

Fnd x and y if $\left(\begin{array}{c}x+2y\\ 2x-y\end{array}\right)=\left(\begin{array}{c}6\\ -8\end{array}\right)$

• A. x = 2, y = -4
• B. x = -2, y = 4
  
• C. x = 4, y = -2
  
• D. x = -4, y = 2

Answer 1

The correct option is B

x = -2, y = 4

The given two matrices are equal
$\Rightarrow$ x + 2y = 6…….(i)
$\Rightarrow$ 2x - y = -8…….(ii)
Eq (ii) x 2
4x - 2y = -16 …. (iii)
Adding (iii) and (i)
5x = -10
x = -2,
Substituting in eq (i)
-2 + 2y = 6
2y = 8 or y = 4.