How do you find the solution set for x+9y=-1, 2x+4y=5?

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Answer 1 · 2015-08-06T10:59:59

${(x = 7/2), (y=-1/2) :}$

You could solve this system of equations by suing the substitution method.

To do that, use the first equation to write $x$ as a function of $y$

$x + 9y = -1$

$x = -1 - 9y$

Now use this expression in the second equation - this will get you the value of $y$

$2x + 4y = 5$

$2 * (-1-9y) +4y = 5$

$-2 - 18y + 4y = 5$

$-14y = 7 implies y = 7/(-14) = color(green)(-1/2)$

FInally, use the value of $y$ to get the value of $x$

$x = -1 - 9 * (-1/2)$

$x = -1 + 9/2 = color(green)(7/2)$