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Solve the system of equations exponential function. Systems of exponential equations and inequalities. Examples of solving homogeneous equations

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Ways to solve systems of equations

To begin with, let us briefly recall what methods of solving systems of equations generally exist.

Exist four main ways solutions of systems of equations:

    Substitution method: take any of these equations and express $y$ in terms of $x$, then $y$ is substituted into the equation of the system, from where the variable $x.$ is found. After that, we can easily calculate the variable $y.$

    Addition method: in this method it is necessary to multiply one or both equations by such numbers that when both are added together, one of the variables "disappears".

    Graphical method: both equations of the system are displayed on the coordinate plane and the point of their intersection is found.

    The method of introducing new variables: in this method, we do the replacement of some expressions to simplify the system, and then apply one of the above methods.

Systems of exponential equations

Definition 1

Systems of equations consisting of exponential equations, are called a system of exponential equations.

We will consider the solution of systems of exponential equations using examples.

Example 1

Solve a system of equations

Picture 1.

Solution.

We will use the first method to solve this system. First, let's express $y$ in the first equation in terms of $x$.

Figure 2.

Substitute $y$ into the second equation:

\ \ \[-2-x=2\] \ \

Answer: $(-4,6)$.

Example 2

Solve a system of equations

Figure 3

Solution.

This system is equivalent to the system

Figure 4

We apply the fourth method for solving equations. Let $2^x=u\ (u >0)$ and $3^y=v\ (v >0)$, we get:

Figure 5

We solve the resulting system by the addition method. Let's add the equations:

\ \

Then from the second equation, we get that

Returning to the replacement, got new system exponential equations:

Figure 6

We get:

Figure 7

Answer: $(0,1)$.

Systems of exponential inequalities

Definition 2

Systems of inequalities consisting of exponential equations are called a system of exponential inequalities.

We will consider the solution of systems of exponential inequalities using examples.

Example 3

Solve the system of inequalities

Figure 8

Solution:

This system of inequalities is equivalent to the system

Figure 9

To solve the first inequality, recall the following equivalence theorem for exponential inequalities:

Theorem 1. The inequality $a^(f(x)) >a^(\varphi (x)) $, where $a >0,a\ne 1$ is equivalent to the set of two systems

\ \ \

Answer: $(-4,6)$.

Example 2

Solve a system of equations

Figure 3

Solution.

This system is equivalent to the system

Figure 4

We apply the fourth method for solving equations. Let $2^x=u\ (u >0)$ and $3^y=v\ (v >0)$, we get:

Figure 5

We solve the resulting system by the addition method. Let's add the equations:

\ \

Then from the second equation, we get that

Returning to the replacement, I received a new system of exponential equations:

Figure 6

We get:

Figure 7

Answer: $(0,1)$.

Systems of exponential inequalities

Definition 2

Systems of inequalities consisting of exponential equations are called a system of exponential inequalities.

We will consider the solution of systems of exponential inequalities using examples.

Example 3

Solve the system of inequalities

Figure 8

Solution:

This system of inequalities is equivalent to the system

Figure 9

To solve the first inequality, recall the following equivalence theorem for exponential inequalities:

Theorem 1. The inequality $a^(f(x)) >a^(\varphi (x)) $, where $a >0,a\ne 1$ is equivalent to the set of two systems

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