How do solve the following linear system?: $3 x - y = 7, 11 x + 3 y + 7 = 0$ $3x-y=7 , 11x + 3y + 7 = 0$ ?

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Answer 1 · 2016-04-11T05:54:37

The solution for the system of equations is:
$x = \frac{7}{10}$ $color(green)(x = 7 / 10$

$y = \frac{- 49}{10}$ $color(green)(y = (- 49) / 10$

$3 x - y = 7$ $3x - y = 7$ , multiplying by $3$ $3$
$9 x - 3 y = 21$ $9x - color(blue)(3y )= 21$ .....................equation $(1)$ $(1)$

$11 x + 3 y = - 7$ $11x + color(blue)( 3y) = - 7$ ................equation $(2)$ $(2)$

Solving by elimination.

Adding equations $1$ $1$ and $2$ $2$ eliminates $3 y$ $color(blue)(3y$

$9x - cancelcolor(blue)(3y )= 21$

$11x + cancelcolor(blue)( 3y) = - 7$

$20x = 14$

$x = 14 / 20$

$color(green)(x = 7 / 10$

Finding $y$ from equation $1$

$3x - y = 7$

$3x - 7 = y$

$3 * color(green)(7/10) - 7 = y$

$21/10 - 7 = y$

$(21 - 70) / 10 = y$

$(- 49) / 10 = y$

$color(green)(y = (- 49) / 10$

How do solve the following linear system?: 3x-y=7 , 11x + 3y + 7 = 0 3x−y=7,11x+3y+7=0 3x-y=7 , 11x + 3y + 7 = 0 ?