How do you solve 4x-y=-6 and x-2y=-5?

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Answer 1 · 2015-09-30T17:21:23

The solutions are
$x = - 1, y = 2$ $color(blue)(x=-1,y=2$

$4 x - y = - 6$ $color(blue)(4x)-y=-6$ ....equation $(1)$ $(1)$

$x - 2 y = - 5$ $x-2y=-5$ , multiplying this equation by $4$ $4$
$4 x - 8 y = - 20$ $color(blue)(4x)-8y=-20$ ....equation $(2)$ $(2)$

Solving by elimination :
Subtracting equation $2$ $2$ from $1$ $1$

$4 x - y = - 6$ $color(blue)(4x)-y=-6$
$-cancelcolor(blue)(4x)+8y=+20$

$7y=14$

$y=14/7$

$color(blue)(y=2$

Finding $x$ by substituting $y$ in equation $1$

$4x-y=-6$

$4x=-6+y$

$4x=-6+2$

$4x=-4$

$color(blue)(x=-1$