Chapter 9: Problem 13
Solve the system of equations by applying the substitution method. $$\begin{aligned}&x+y=2\\\&x^{2}+y^{2}=2\end{aligned}$$
Short Answer
Expert verified
The solution is \( (x, y) = (1, 1) \). Both equations are satisfied.
Step by step solution
01
Solve for One Variable
Start with the first equation: \( x + y = 2 \). Solve for \( y \), yielding \( y = 2 - x \). This expression allows us to substitute \( y \) in terms of \( x \) into the second equation.
02
Substitute and Simplify
Substitute \( y = 2 - x \) into the second equation \( x^2 + y^2 = 2 \). So, we have: \[ x^2 + (2 - x)^2 = 2. \] Expanding \((2-x)^2\) gives \(4 - 4x + x^2\). The equation becomes \( x^2 + 4 - 4x + x^2 = 2 \). Simplify this to \( 2x^2 - 4x + 4 = 2 \).
03
Set the Equation to Zero
Subtract 2 from both sides to set the equation to 0: \( 2x^2 - 4x + 2 = 0 \). Divide every term by 2 to simplify: \( x^2 - 2x + 1 = 0 \).
04
Solve the Quadratic
Recognize \( x^2 - 2x + 1 = (x-1)^2 \). Thus, \((x-1)^2 = 0\) which means \( x = 1 \). This is the only solution for \( x \).
05
Find the Corresponding \( y \) Value
Substitute \( x = 1 \) back into \( y = 2 - x \) to find \( y \). So, \( y = 2 - 1 = 1 \).
06
Verify the Solution
Check the solution \( (x, y) = (1, 1) \) against both original equations. For \( x + y = 2 \), \( 1 + 1 = 2 \) which is correct. For \( x^2 + y^2 = 2 \), \( 1^2 + 1^2 = 2 \) confirming the solution is correct.
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
System of Equations
A system of equations consists of two or more equations that share the same variables. Solving a system of equations requires finding values for the variables that satisfy all the equations simultaneously. In this exercise, we deal with a system of two equations:
To apply this method correctly, solve one equation for one variable and substitute it into the other equation. This reduces the two equations to a single equation with one variable, making it easier to solve.
- Equation 1: \( x + y = 2 \)
- Equation 2: \( x^2 + y^2 = 2 \)
To apply this method correctly, solve one equation for one variable and substitute it into the other equation. This reduces the two equations to a single equation with one variable, making it easier to solve.
Quadratic Equation
In the process of solving our system, we encounter a quadratic equation. Quadratic equations are equations of the form \( ax^2 + bx + c = 0 \), where \( a \), \( b \), and \( c \) are constants. In this case, solving for \( x \) after substitution yields a simplified quadratic:
- \( 2x^2 - 4x + 4 = 2 \), which simplifies to \( x^2 - 2x + 1 = 0 \)
Solution Verification
Once a solution is found, verification is crucial to ensure accuracy and correctness. For our solution, \( (x, y) = (1, 1) \), we substitute these values back into the original equations to verify:
- For \( x + y = 2 \), substituting gives \( 1 + 1 = 2 \), which confirms the solution satisfies the first equation.
- For \( x^2 + y^2 = 2 \), substituting gives \( 1^2 + 1^2 = 2 \), also confirming the solution satisfies the second equation.