SOLUTION: help me pls to solve this system of equation by substitution? -3x+3y=4,-x+y=3

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Question 325293: help me pls to solve this system of equation by substitution?
-3x+3y=4,-x+y=3
Answer by jim_thompson5910(35256) About Me  (Show Source):
You can put this solution on YOUR website!

Start with the given system of equations:

system%28-3x%2B3y=4%2C-x%2By=3%29



Now in order to solve this system by using substitution, we need to solve (or isolate) one variable. I'm going to solve for y.




So let's isolate y in the second equation

-x%2By=3 Start with the second equation


y=3%2Bx Add x to both sides


y=x%2B3 Rearrange the equation


---------------------

Since y=x%2B3, we can now replace each y in the second equation with x%2B3 to solve for x



-3x%2B3highlight%28%28x%2B3%29%29=4 Plug in y=x%2B3 into the second equation. In other words, replace each y with x%2B3. Notice we've eliminated the y variables. So we now have a simple equation with one unknown.



-3x%2B3x%2B%283%29%283%29=4 Distribute 3 to x%2B3


-3x%2B3x%2B9=4 Multiply


9=4 Combine like terms on the left side


0=4-9Subtract 9 from both sides


0=-5 Combine like terms on the right side


Since this equation is NEVER true for any x value, this means there are no solutions.


So the system is inconsistent.