How do you solve the system of equations -x-y=15 and -8x+8y=24?
1 Answer
Explanation:
The system of equations given to you looks like this
{( -color(white)(1)x - color(white)(1)y = 15), (-8x + 8y = 24) :}
Notice that one equation features
To do that, multiply the first equation by
{( -color(white)(1)x - color(white)(1)y = 15" " | xx 8), (-8x + 8y = 24) :}
this will get you
{ ( -8x - 8y = 120), (-8x + 8y = color(white)(1)24) :}
Now you're ready to add the two equations
{ ( -8x - 8y = 120), (-8x + 8y = color(white)(1)24) :}
color(white)(aaaaaaaaaaaaaaa)/color(white)(a)
-8x + (-8x) - color(red)(cancel(color(black)(8y))) + color(red)(cancel(color(black)(8y))) = 120 + 24
-16x = 144 implies x = 144/(-16) = -9
Take this value of
- (-9) - y = 15
-y = 15 - 9 implies y = -6
Therefore, the two solutions to your system of equations are
{(x=-9), (y=-6) :}