The concept of the system and its rozvytku
Definition: If the task is to find all common solutions of two (or more) inequalities on the one or more variables, then we say that it is necessary razvesti system of inequalities.
Definition: Rozvyazka system — the value of a variable or such an ordered set of values smya that satisfies all the inequalities in the system, that is rozvyazka system of two or more inequalities with 
unknown call such an ordered set a lot of numbers, after the substitution of which into the system is unknown, all inequalities turn into true numerical equality.
Definition: Razvesti the system of equations is to find all its interchanges , or to prove that they are not.
If the system has no solution, then it is incompatible.
Example systems of inequalities
the system of three equations with two variables
Couple 
that is 
one of rozvytku system
Scheme the solution of systems of inequalities with one variable
- Rozvadov each inequality separately.
- To find all joint junction of these inequalities.
Scheme the solution of systems of inequalities with multiple variables
- Rozvadov the system of inequalities as a system of equations by changing, for a while, the inequality sign to an equal sign.
- To change the sign back and to find common solutions these inequities.
Examples of solving systems of equations
Solution by graphical methods
Example 1
Rozwarte equation: 
Solutions:
Building graphics 
Building graphics will see that the graphs intersect at the point 
Answer: 
The decision of the method of substitution
Example 2
Rozwarte equation: 
Solutions:
From the first equation we Express 
And substitute the resulting expression into the second equation of the system:
The resulting value 
is substituted into the expression 
Answer: 
Solution by adding
Example 3
Rozwarte equation: 
Solutions:
Need to get rid of a variable 
poslano Multiply the first equation of system 3 and the second by 2.
Add pocino equation and get: 
Find the value 
of the first equation of the system: 
Answer: 
Remark: the method add can be multiplied not only on positive numbers, and negative.
How rozwiazywanie the system of equations to solve only to You.