How do solve the following linear system?: $-9x+5y=1 , -x+5y=-13$ ?

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Answer 1 · 2015-11-26T12:15:44

$x=-7/4$ , $y=-59/20$

From the second equation, you have that $x=5y+13$ . Substitute this expression for $x$ in the first equation to have

$-9(5y+13)+5y=1$ . Expand:

$-45y-117+5y=1$ . Isolate the $y$ terms:

$-40y = 118$ . Solve for $y$ :

$y=-118/40 = -59/20$ .

Once $y$ is known, we can find back $x$ :

$x=5y+13 = 5*(-59/20)+13 = -7/4$ .

How do solve the following linear system?: -9x+5y=1 , -x+5y=-13 -9x+5y=1 , -x+5y=-13 ?