Chapter 10: Problem 42
Use the graphical method to find all solutions of the system of equations, correct to two decimal places. \(\left\\{\begin{aligned} x^{2}+y^{2} &=17 \\ x^{2}-2 x+y^{2} &=13 \end{aligned}\right.\)
Short Answer
Expert verified
The solutions are \( (2, 3.61) \) and \( (2, -3.61) \).
Step by step solution
01
Rewrite the Equations
Start by rewriting the given equations for clarity. We have two equations: 1. \( x^2 + y^2 = 17 \) 2. \( x^2 - 2x + y^2 = 13 \)
02
Simplify Second Equation
Subtract the second equation from the first to eliminate \( y^2 \): \( (x^2 + y^2) - (x^2 - 2x + y^2) = 17 - 13 \). This simplifies to \( 2x = 4 \), so \( x = 2 \).
03
Solve for y
Substitute \( x = 2 \) back into the first equation: \( 2^2 + y^2 = 17 \). This simplifies to \( 4 + y^2 = 17 \) or \( y^2 = 13 \). Therefore, \( y = \pm \sqrt{13} \).
04
Identify Solution Pairs
We have \( y = \pm \sqrt{13} \). Thus, the solutions are: \( (x, y) = (2, \sqrt{13}) \) and \( (2, -\sqrt{13}) \).
05
Convert to Decimal Form
Calculate the decimal form of \( \sqrt{13} \): \( \sqrt{13} \approx 3.61 \). Therefore, the solutions are \( (2, 3.61) \) and \( (2, -3.61) \).
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
System of Equations
When dealing with a system of equations, we are working with multiple equations that share common variables. In this case, the variables are \( x \) and \( y \). Our goal is to find values for these variables that satisfy both equations at the same time. It's like searching for points where two curves intersect on a graph. The given equations represent two circles:
This is the essence of the graphical method: finding the shared solutions visually by drawing the equations on the same plane.
- \( x^2 + y^2 = 17 \) is a circle centered at the origin with a radius of \( \sqrt{17} \)
- \( x^2 - 2x + y^2 = 13 \) can be rewritten by completing the square to represent another circle.
This is the essence of the graphical method: finding the shared solutions visually by drawing the equations on the same plane.
Solution Pairs
Solution pairs are the values of \( x \) and \( y \) that solve a system of equations simultaneously. For this problem, it means identifying the points where the two circles intersect.After simplifying our equations, we found the values of \( x \) and corresponding \( y \) values that make both equations true:
- First, we simplified using subtraction to find \( x = 2 \)
- Substituted \( x = 2 \) back into the original equations to solve for \( y \)
- Calculated that \( y = \pm \sqrt{13} \), giving us two pairs: \((2, \sqrt{13})\) and \((2, -\sqrt{13})\)
Decimal Approximation
Decimal approximation helps express solution pairs in more practical, numerical terms. While \( \pm \sqrt{13} \) is a precise answer, everyday calculations prefer decimals. To convert \( \sqrt{13} \) to decimal form, we determine that \( \sqrt{13} \approx 3.61 \). This helps us express our solution pairs in familiar terms:
- \( (2, 3.61) \) and \( (2, -3.61) \)
Simplification of Equations
Simplification reduces the complexity of equations, making them easier to solve. In this problem, simplification was key to finding the values of \( x \) and \( y \). Here's how we simplified:
- By subtracting the second equation from the first, we eliminated \( y^2 \), simplifying our system to \( 2x = 4 \)
- We solved for \( x \) quickly, getting \( x = 2 \)