Answer:
The answer is A.
Step-by-step explanation:
So we have the two equations:
To make a substitution of the second equation into the first equation, we need to isolate the <em>y </em>variable in the second equation. Thus:
Now, we can substitute this into the first equation. Therefore:
Explanation:
Basically, you can do it in many ways. But just, in my opinion, exactly linear algebra was made for such cases.
the optimal way is to do it with Cramer's rule.
First, find the determinant and then find the determinant x, y, v, u.
Afterward, simply divide the determinant of variables by the usual determinant.
eg. and etc.
I think that is the best way to solve it without a hustle of myriad of calculations reducing it to row echelon form and solving with Gaussian elimination.