Question

Solve by elimination:

4x+7y =8
-8x -14y= 5

Answer 1

$\left \{ {\big{4x+7y =8} \atop\big {-8x -14y= 5}} \right. \\\\ \left \{ {\big{4x+7y =8\ /\cdot2} \atop\big {-8x -14y= 5\ \ }} \right. \\\\ \left \{ {\big{8x+14y =16} \atop\big {-8x -14y= 5 }} \right. \\----------\\0=21\\no\ solution$

Answer 2

$\begin{cases}4x+7y =8 \ \ /\cdot 2 \\ -8x -14y= 5 \end{cases}\\ \\\begin{cases}8x+14y =16 \ \ \\ -8x -14y= 5 \end{cases}\\ + \---------\\0 \neq 21 \\ \\ Answer : \ the \ system \ has \ no \ solution$