Quandaries and Queries


I'm take grade 10 academic math and we just started the substitution method. My question is, If you have a problem for ex.


and for the first step your suppose to Isolate one variable. My teacher says to take the first one that's isolated to start with. But in this problem there is 2 already isolated, y and x. The point where i got stuck is here:
Now i don't know how to do the rest of the steps. I'm stuck and i need your help. Thanks a lot math central:)
From, Kayla



Hi Kayla,

You have the two equations

y = x - 1
y = 2x - 3

and you have correctly recognized that the first equation already has y isolated. The method is then to replace y in the second equation by this value. That is, in the second equation, every place you see y, substitute x - 1. The second equation then becomes

x - 1 = 2x - 3

Does this help? Let me know if you still have difficulty finishing this problem.



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