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Solving a System by Substitution In Exercises \(15-24\) , solve the system by the method of substitution. $$\left\\{\begin{aligned} \frac{1}{5} x+\frac{1}{2} y &=8 \\ x+y &=20 \end{aligned}\right.$$

Short Answer

Expert verified
The values of x and y that satisfies the system of equations are \(x = 20/3\) and \(y = 40/3\).

Step by step solution

01

Isolate Variable x from the Second Equation

From \(x + y = 20\), one can isolate x as \(x = 20 - y\)
02

Substitute for x into the First Equation

Take \(x = 20 - y\) and substitute it into the first equation, resulting in \(\frac{1}{5}(20 - y) + \frac{1}{2}y = 8\). Simplify it by distributing and combining like terms, getting \(\frac{1}{2}y - \frac{1}{5}y = 8 - 4\) which leads to \(3y/10=4\). Multiplying both sides of the equation by 10/3 you get \(y = 40/3\).
03

Substitute Value of y into the Isolated Variable x

Now take \(y = 40/3\) and substitute it into \(x = 20 - y\). This leads to \(x = 20 - 40/3\) which simplifies to \(x = 60/3 - 40/3\) hence \(x = 20/3\).
04

Solution

The solution to the system of equations is \(x = 20/3\) and \(y = 40/3\).

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Key Concepts

These are the key concepts you need to understand to accurately answer the question.

System of Equations
When tackling algebraic concepts, one of the fundamental ideas you'll encounter is the system of equations. It consists of two or more equations involving the same set of variables. The goal is to find a common solution to these equations, that is, values for the variables that make all equations true simultaneously.

A common type of system you might come across is the linear system of equations, where each equation is a straight line if graphed. When solving these systems, one is typically looking for the point(s) where these lines intersect, as this point represents the values that solve each equation in the system.

To solve such a system, you may use several methods, such as graphing, elimination, or substitution. The substitution method is particularly useful when one equation can be easily solved for one variable in terms of the other.
Substitution Method
The substitution method is often employed when one of the equations in a system can easily be solved for one variable. Essentially, this method involves rearranging one equation to express one variable in terms of the other, and then 'substituting' this expression into the second equation.

For example, if you isolate 'x' in one equation and you get an expression like x = 20 - y, this expression is then substituted in place of 'x' in the other equation(s). This substitution simplifies the system to a single equation in one variable, which is typically easier to solve. Once the value of one variable is found, it is substituted back into one of the original equations to find the value of the other variable.

The substitution method is a powerful tool, as it overall simplifies the system, making it easier for students to reach the solution step by step.
Algebraic Equations
In the world of algebra, algebraic equations are the bread and butter. They are statements of equality containing variables, numbers, and operations. Solving an algebraic equation is about finding the value or values that make the equation true.

To solve these equations, one must understand how to manipulate them using various algebraic properties, such as the distributive property, combining like terms, and the inverse operations of addition, subtraction, multiplication, and division.

When dealing with a system of equations, it’s essential to apply these principles consistently to isolate variables and solve the equations step by step. Precision in simplifying expressions and solving for variables is key to correctly determining the solution to the equations.
Precalculus
Moving toward a more advanced understanding of mathematics, we venture into the realm of precalculus. This field lays the groundwork for the study of calculus and includes a review of algebra, geometry, and functions, among other topics.

In precalculus, you deepen your understanding of algebraic concepts such as systems of equations and learn how to tackle them with greater complexity. It expands on your ability to analyze and solve equations, introducing new functions and the behavior of their graphs.

Understanding how to solve systems of equations by methods like substitution is essential in precalculus. It prepares you not only for calculus but also develops problem-solving skills that are applicable to numerous mathematical scenarios. It is an opportunity to perfect your algebraic techniques before taking on the challenges of calculus.

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