Add the two equations to eliminate y : 2 x = 10 .
Solve for x : x = 5 .
Substitute the value of x into one of the original equations to solve for y : 5 + y = 6 , so y = 1 .
The solution set is { ( 5 , 1 ) } .
Explanation
Analyze the problem We are given a system of two linear equations with two variables, x and y :
x + y = 6 x − y = 4
Our goal is to solve this system using the addition method, which involves adding the equations in such a way that one of the variables is eliminated.
Eliminate y and solve for x To eliminate y , we can simply add the two equations:
( x + y ) + ( x − y ) = 6 + 4
This simplifies to:
2 x = 10
Now, we can solve for x by dividing both sides by 2:
x = 2 10 = 5
So, x = 5 .
Solve for y Now that we have the value of x , we can substitute it into either of the original equations to solve for y . Let's use the first equation:
x + y = 6
Substitute x = 5 :
5 + y = 6
Subtract 5 from both sides to solve for y :
y = 6 − 5 = 1
So, y = 1 .
State the solution The solution to the system of equations is the ordered pair ( x , y ) = ( 5 , 1 ) .
Examples
Systems of equations are used in various real-world applications, such as determining the break-even point for a business, calculating the optimal mix of ingredients in a recipe, or modeling supply and demand in economics. For example, suppose a bakery sells cookies and cakes. Let x be the number of cookies and y be the number of cakes. If the total revenue is given by x + y = 6 (in thousands of dollars) and the difference in production cost is x − y = 4 (in thousands of dollars), solving this system helps the bakery determine the optimal production levels for cookies and cakes to meet their financial goals.
The solution to the system of equations is the ordered pair (5, 1). Therefore, the solution set is {( 5 , 1 )} .
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