Rewriting the Equation as a System of Equations

Oct 13, 2025 by wbrum.org 121 views

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Introduction

Quadratic equations are a fundamental concept in algebra, and solving them is a crucial skill for students to master. One way to solve quadratic equations is by using a system of equations, which involves graphing two equations on the same coordinate plane and finding the intersection point(s). In this article, we will describe the graph that would be used to solve the equation $-x^2+4=x+2$ using a system of equations and explain how to use the graph to find the solution(s).

The Equation

The given equation is $-x^2+4=x+2$ . To solve this equation using a system of equations, we need to rewrite it in the form of two separate equations. We can do this by subtracting $x$ from both sides and adding $2$ to both sides, resulting in:

-x^2 - x + 2 = 0

Rewriting the Equation as a System of Equations

To rewrite the equation as a system of equations, we can set $y = -x^2 - x + 2$ . This gives us two equations:

y = -x^2 - x + 2

y = 0

Graphing the Equations

To graph the equations, we can use a graphing calculator or a computer algebra system. The graph of the first equation, $y = -x^2 - x + 2$ , is a parabola that opens downward. The graph of the second equation, $y = 0$ , is a horizontal line.

Finding the Intersection Point(s)

The intersection point(s) of the two graphs represent the solution(s) to the equation. To find the intersection point(s), we need to find the point(s) where the two graphs intersect. This can be done by setting the two equations equal to each other and solving for $x$ .

Solving for x

Setting the two equations equal to each other, we get:

-x^2 - x + 2 = 0

We can solve this equation using the quadratic formula:

x = \frac{-b \pm \sqrt{b^2 - 4ac}}{2a}

In this case, $a = -1$ , $b = -1$ , and $c = 2$ . Plugging these values into the quadratic formula, we get:

x = \frac{1 \pm \sqrt{1 + 8}}{-2}

x = \frac{1 \pm \sqrt{9}}{-2}

x = \frac{1 \pm 3}{-2}

This gives us two possible values for $x$ :

x = \frac{1 + 3}{-2} = -2

x = \frac{1 - 3}{-2} = 1

Finding the Corresponding y-Values

To find the corresponding $y$ -values, we can plug the $x$ -values into one of the original equations. Let's use the first equation:

y = -x^2 - x + 2

Plugging in $x = -2$ , we get:

y = -(-2)^2 - (-2) + 2

y = -4 + 2 + 2

y = 0

Plugging in $x = 1$ , we get:

y = -(1)^2 - (1) + 2

y = -1 - 1 + 2

y = 0

Conclusion

In this article, we described the graph that would be used to solve the equation $-x^2+4=x+2$ using a system of equations. We explained how to use the graph to find the solution(s) by finding the intersection point(s) of the two graphs. We also solved for $x$ using the quadratic formula and found the corresponding $y$ -values. The solutions to the equation are $x = -2$ and $x = 1$ , with corresponding $y$ -values of $y = 0$ .

Graphing the Solution

The graph of the solution is a point on the coordinate plane, representing the intersection point of the two graphs. The graph is a point with coordinates $(x, y) = (-2, 0)$ and $(x, y) = (1, 0)$ .

Interpretation of the Graph

The graph represents the solution to the equation $-x^2+4=x+2$ . The point $(x, y) = (-2, 0)$ represents the solution $x = -2$ , and the point $(x, y) = (1, 0)$ represents the solution $x = 1$ . The graph shows that the two solutions are $x = -2$ and $x = 1$ , with corresponding $y$ -values of $y = 0$ .

Real-World Applications

The equation $-x^2+4=x+2$ has many real-world applications, such as modeling the motion of an object under the influence of gravity or the growth of a population over time. The solutions to the equation can be used to make predictions about the behavior of the object or population.

Conclusion

In conclusion, the graph that would be used to solve the equation $-x^2+4=x+2$ using a system of equations is a parabola and a horizontal line. The intersection point(s) of the two graphs represent the solution(s) to the equation. We solved for $x$ using the quadratic formula and found the corresponding $y$ -values. The solutions to the equation are $x = -2$ and $x = 1$ , with corresponding $y$ -values of $y = 0$ . The graph represents the solution to the equation and has many real-world applications.

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Q: What is a system of equations?

A: A system of equations is a set of two or more equations that are solved simultaneously to find the values of the variables. In the case of solving quadratic equations, we can rewrite the equation as a system of equations by setting $y = -x^2 - x + 2$ and $y = 0$ .

Q: Why do we need to rewrite the equation as a system of equations?

A: We need to rewrite the equation as a system of equations because it allows us to use the graphing method to find the solution(s) to the equation. By graphing the two equations on the same coordinate plane, we can find the intersection point(s) of the two graphs, which represent the solution(s) to the equation.

Q: How do we find the intersection point(s) of the two graphs?

A: To find the intersection point(s) of the two graphs, we need to set the two equations equal to each other and solve for $x$ . This can be done using the quadratic formula or by factoring the equation.

Q: What is the quadratic formula?

A: The quadratic formula is a formula that is used to solve quadratic equations. It is given by:

x = \frac{-b \pm \sqrt{b^2 - 4ac}}{2a}

Q: How do we use the quadratic formula to solve the equation?

A: To use the quadratic formula to solve the equation, we need to plug in the values of $a$ , $b$ , and $c$ into the formula. In this case, $a = -1$ , $b = -1$ , and $c = 2$ . Plugging these values into the formula, we get:

x = \frac{1 \pm \sqrt{1 + 8}}{-2}

x = \frac{1 \pm \sqrt{9}}{-2}

x = \frac{1 \pm 3}{-2}

Q: What are the solutions to the equation?

A: The solutions to the equation are $x = -2$ and $x = 1$ , with corresponding $y$ -values of $y = 0$ .

Q: How do we interpret the graph of the solution?

A: The graph of the solution is a point on the coordinate plane, representing the intersection point of the two graphs. The graph is a point with coordinates $(x, y) = (-2, 0)$ and $(x, y) = (1, 0)$ .

Q: What are some real-world applications of the equation?

A: The equation $-x^2+4=x+2$ has many real-world applications, such as modeling the motion of an object under the influence of gravity or the growth of a population over time. The solutions to the equation can be used to make predictions about the behavior of the object or population.

Q: Can we use other methods to solve the equation?

A: Yes, we can use other methods to solve the equation, such as factoring or using the quadratic formula. However, the graphing method is a useful tool for visualizing the solution and understanding the behavior of the equation.

Q: What are some common mistakes to avoid when solving quadratic equations?

A: Some common mistakes to avoid when solving quadratic equations include:

Not rewriting the equation as a system of equations
Not using the correct values of $a$ , $b$ , and $c$ in the quadratic formula
Not checking for extraneous solutions
Not interpreting the graph of the solution correctly

Q: How can we check our solutions?

A: We can check our solutions by plugging them back into the original equation and verifying that they are true. We can also use the graphing method to check our solutions by graphing the two equations on the same coordinate plane and verifying that the intersection point(s) match the solutions we found.

Q: What are some tips for solving quadratic equations?

A: Some tips for solving quadratic equations include:

Always rewrite the equation as a system of equations
Use the quadratic formula or factoring to solve the equation
Check for extraneous solutions
Interpret the graph of the solution correctly
Use the graphing method to visualize the solution and understand the behavior of the equation.