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Solve each system by the substitution method. \(\left\\{\begin{array}{l}{2 x-3 y=-13} \\ {y=2 x+7}\end{array}\right.\)

Short Answer

Expert verified
The solutions to the system of equations are (1, -2) and (2, 1).

Step by step solution

01

Solve second equation for y

To start with, rearrange the equation 3x - y = 5 to get the value of y in terms of x. This results in y = 3x - 5.
02

Substitute y in first equation

Now substitute y from step 1 (3x - 5) into first equation x² + y² = 5. This gives \(x^{2} + (3x - 5)^{2} = 5\). This simplifies to \(x^{2} + 9x^{2} - 30x + 25 = 5\), which can be further simplified to \(10x^{2} - 30x + 20 = 0\). This is a quadratic equation which can be simplified by first dividing every term by 10, the result being \(x^{2} - 3x + 2 = 0\).
03

Solve for x from the quadratic equation

Now solve the quadratic equation \(x^{2} - 3x + 2 = 0\) for x. This equation factors to \((x - 1)(x - 2) = 0\). So, x = 1 and x = 2 are the solutions.
04

Substitute x values into second equation to get y values

Substitute x = 1 into 3x - y = 5 to get y = -2 and substitute x = 2 into 3x - y = 5 to get y = 1. Therefore, the solution set is {(1,-2), (2,1)}.

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Key Concepts

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

Quadratic Equations
Quadratic equations are mathematical expressions where the highest exponent of a variable is 2. They are typically written in the standard form \(ax^2 + bx + c = 0\), where \(a\), \(b\), and \(c\) are constants, and \(x\) represents an unknown variable. These equations often appear in problems involving area, projectile motions, or any scenario where a parabolic pattern or curve is present.
Quadric equations can be solved using multiple methods, such as:
  • Factoring
  • Using the quadratic formula
  • Completing the square
In our exercise, we encountered a quadratic equation when we substituted for \(y\) into \(x^2 + y^2 = 5\), resulting in the equation \(x^2 - 3x + 2 = 0\). By factoring, we found the solutions for \(x\). This highlights the importance of understanding how to manipulate and solve quadratic equations in various contexts.
System of Equations
A system of equations consists of multiple equations that share common variables. The goal is to find the values of these variables that satisfy all the equations at once. These systems can often be solved through different strategies:
  • Substitution
  • Elimination
  • Graphical methods
In our provided exercise, we have a system of equations consisting of a quadratic equation and a linear equation. By using the substitution method, we solved for one variable in terms of another using one equation, then substituted this back into the second to find specific values. This method is particularly handy when one of the equations is already solved for one variable, or can be easily rearranged, making it efficient and straightforward.
Factoring Polynomials
Factoring polynomials is a pivotal skill in algebra that simplifies expressions and solves equations. It involves expressing a polynomial as a product of its factors. For quadratic equations, this usually involves breaking down the expression into two binomials.
In our problem, after substitution, we simplified the quadratic polynomial \(x^2 - 3x + 2\) to solve for \(x\). By factoring it into \((x - 1)(x - 2) = 0\), we quickly found the solutions \(x = 1\) and \(x = 2\). This illustrates how factoring not only aids in finding solutions efficiently but also in understanding the roots of polynomial equations. Remember, while not all polynomials are easily factorable, those that are can significantly speed up the problem-solving process.

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