How do solve the following linear system?: $-9x + 6y = -2 , x-3y=-2$ ?

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Answer 1 · 2016-01-31T08:44:05

$(x,y)=(6/7,20/21)$

Solve by elimination:

$-9x+6y=-2$

$x-3y=-2$

We can eliminate $-9x$ in the first equation by $x$ in the second equation if we multiply it with $9$ to get $9x$ :

$rarr9(x-3y=-2)$

$rarr9x-27y=-18$

Now add both of the equations:

$rarr(-9x+6y=-2)+(9x-27y=-18)$

$rarr -21y=-20$

$rarry=(-20)/-21=20/21$

(Because, $(-n)/(-p)$ $=(+n)/(+p)$ )

Substitute the value to the second equation:

$rarrx-3(20/21)=-2$

$rarrx-60/21=-2$

$rarrx-20/7=-2$

$rarrx=-2+20/7$

$rarrx=-14/7+20/7$

$rarrx=6/7$

How do solve the following linear system?: -9x + 6y = -2 , x-3y=-2 -9x + 6y = -2 , x-3y=-2 ?