In which quadrant does the point (–10, 9) lie?
2 answers:
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Elimination Method
If we multiply the equation 3 by (-1) we obtain this:
If we add them we obtain 0, therefore there are infinite solutions. So, let's write it in terms of Z
1. Using the 3rd equation we can obtain X(Y,Z)
2. We can replace this value of X in the 1st and 2nd equations
3. If we simplify:
4. We can obtain Y from this two equations:
5. Now, we need to obtain X(Z). We can replace Y in X(Y,Z)
6. If we simplify, we obtain:
7. In conclusion, we obtain that
(X,Y,Z) =
Answer: (D)
Explanation:
Just a note on writing down these expressions: I recommend using parentheses whenever you can to avoid misinterpretation. An expression 1/x-1/y / 1/x+1/y could be interpreted by someone as 1/x-(1/y / 1/x)+1/y, which is a different thing.