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# Two Variables Equation

Two Variables Equation
If there are two unknown variables in an equation, and the degree of unknown variable is one, then this equation is called two variables one degree equation. Example.
Example
equation (1) has variables x and y, both are one degree, then equation (1) is called two variables one degree equation.
Group of Two Variables Equation
The group is constructed by two independent equations, each of them is two variable one degree equation. The number of equations in the group is equal to the number of variables in the group.
Example
equations (1) and (2) are within a group, both are independent.
Solution of Two Variables Equation
In the group of two variables one degree equation, the values of the unknown variables which make the left side of the equation is equal to the right side of the equation is called the solution.
Example
equations (3) and (4) are solutions of this group.
Removing Variable Using Substitution Method
Example
Steps using substitution method
Step 1: Change equation (1) to express variable x in terms of y, such that, x = 3 - 2y , which is equation (3).
Step 2: Substitute equation (2) for equation (3) to remove the variable x.
Step 3: Solve this one variable equation, we get y = 1.
Step 4: Substitute equation (3) for the value of y to get the value of x.
Removing Variable Using Add and Subtract Method
Example