Question
For the solution of the system of equations above, what is the value of ?
- -4
- -2
- 0
- 2
Hint:
Hint:
We are given two linear equations in two variables. To find the value
of x, we need to solve them. We need to find a way to eliminate y
and get the value of x from the equations. Here, we can do this in a
simple way: by adding the two equations together, since y can be
easily removed then. We get a linear equation in one variable which can be easily solved to get the value of x
The correct answer is: 0
The given equations are
First, we eliminate y by adding the equations together
Simplifying, we get
We have,
Thus, we get
As 
, we must have x =0 .
Thus, the correct option is C).
Note:
The equations can be solved in many other ways like substitution
method which is: to eliminate one variable in any one of the
equations with the help of other equation. As we need to find the
value of x, we try to find the value of y in terms of x from one
equation. Then put that value of y in the other equation to get a linear equation in one variable , which is x.
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