SOLUTION: i do not understand how to solve this problem y=x-9 x+8y=0

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Question 179767This question is from textbook Algebra 1
: i do not understand how to solve this problem y=x-9 x+8y=0 This question is from textbook Algebra 1

Answer by Mathtut(3670) About Me  (Show Source):
You can put this solution on YOUR website!
you can solve it by a number of methods such as substitution or elimination
:
I will use substution for this problem
:
y=x-9.........eq 1
x+8y=0........eq 2
:
take the value of y from eq 1 which is x-9 and plug that into eq 2 for every occurrence of y
:
x+8(x-9)=0
:
x+8x-72=0
:
9x=72
:
highlight%28x=8%29
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now take x's found value and plug that into eq 1 or eq 2. Both will yield the same answer when solving for y. I choose eq 1
:
y=8-9=-1
:
solution:(8,-1)
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If you plug those values into either equation they will be a solution.