Chapter 7: Problem 75
Solve the system of equations. $$ \begin{aligned} (x-2)^{2}+y^{2} &=9 \\ x^{2}+y^{2} &=9 \end{aligned} $$
Short Answer
Expert verified
The solutions are \((1, 2\sqrt{2})\) and \((1, -2\sqrt{2})\).
Step by step solution
01
Equation Simplification
Let's start by simplifying the given equations. We have two equations: 1. \((x-2)^2 + y^2 = 9\) 2. \(x^2 + y^2 = 9\). Notice that both right sides equal 9 and both contain \(y^2\).
02
Subtract Equations
Subtract the second equation from the first to eliminate \(y^2\). \((x-2)^2 + y^2 - (x^2 + y^2) = 9 - 9\) This simplifies to: \((x-2)^2 - x^2 = 0\).
03
Simplify Resulting Equation
Expand \((x-2)^2\) to simplify the expression: \(x^2 - 4x + 4 - x^2 = 0\) This reduces to: \(-4x + 4 = 0\).
04
Solve for x
Solving \(-4x + 4 = 0\) gives: \(-4x = -4\) \(x = 1\).
05
Substitute x into Second Equation
Now, substitute \(x = 1\) back into the second equation \(x^2 + y^2 = 9\): \(1^2 + y^2 = 9\) \(1 + y^2 = 9\).
06
Solve for y
Solve for \(y^2\) by subtracting 1: \(y^2 = 8\) Taking the square root gives \(y = \pm \sqrt{8} = \pm 2\sqrt{2}\).
07
Identify Solution Pair
The solution to the system of equations is: \((x, y) = (1, 2\sqrt{2})\) or \((x, y) = (1, -2\sqrt{2})\).
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Equation Solving
Solving a system of equations involves finding values for the variables that satisfy all the equations simultaneously. In this particular case, we began with two equations which share a common term, \(y^2\). This similarity allowed us to simplify our approach to discover the values of \(x\) and \(y\) that fit both equations.
- We used subtraction to eliminate one of the variables, \(y^2\). This is considered a strategic move in simplifying systems.
- The elimination resulted in an equation that only involved \(x\), making it straightforward to solve for \(x\).
- Once \(x\) was found, back substitution into one of the original equations yielded the solution for \(y\).
Algebra
Algebra is a powerful mathematical tool used to manipulate equations and expressions to find unknown variables. In the exercise, several algebraic techniques were employed:
- Equation expansion: We expanded \((x-2)^2\) to \(x^2 - 4x + 4\) to simplify the problem.
- Like-term cancellation: By subtracting entire equations, similar terms cancel, reducing complexity.
- Transposition and solving: The manipulation of equations to isolate variables, as shown when solving \(-4x + 4 = 0\).
Mathematical Modeling
Mathematical modeling involves representing real-world situations using mathematical concepts and equations. It's like building a bridge between math and the scenarios we encounter in reality.
- In our exercise, the equations could model a geometric shape, particularly circles. The expressions in the equations suggest constraints that the solutions must satisfy, forming a model.
- Finding the intersection point (solution) means identifying where the conditions described by each equation exist simultaneously, much like finding where two circles might intersect.
- Modeling often simplifies decision-making or prediction by allowing complex real-world interactions to be analyzed mathematically.