Name: graphing equations to find intercepts
Uploaded: 2025-11-26T05:44:16.000Z
Duration: 1 min 27 s
Channel: JoVE

方程式をグラフィカルに解くには、 x 値を選択し、方程式から対応する y 値を計算し、これらの点を座標平面にプロットしてグラフを描画します。方程式の解は、グラフが x 軸と交差する x 値であり、これらの点は方程式がゼロに等しい場所を示しています。この方法は、二次方程式を解くのにも役立ちます。二次方程式のグラフがx軸に接触または交差する回数は、方程式が持つ実解の数を示します。まったく触れなければ、本当の解決策はありません。特定の間隔の x 値内の方程式を解くために、グラフはその間隔内の x 値に制限されます。この間隔内の x 切片のみが有効な解と見なされます。2つの方程式の連系をグラフィカルに解くために、両方の方程式がプロットされます。2つのグラフが交差する点は、両方の方程式を満たす解を与えます。ビジネスでは、総コストと総収益が販売ユニットに対してプロットされます。これらのグラフは損益分岐点(収益が特定のユニット数のコストに等しい)で交差します。

グラフによる方程式の解法

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Education

JoVE Core

Math Fundamentals

数学の基礎

Unit

ユニット

Coordinates and Graphs

座標とグラフ

KEY TERMS AND CONCEPTS

主要用語と概念

Solving Equations Graphically

graphing equations to find intercepts

Graphing equations helps students find intercepts and solutions on the coordinate plane. It gives a visual way to solve equations and understand how a function behaves.

To use this method, write the equation in the form y = f(x). The solution to the original equation is the x-value where the graph crosses the x-axis. At that point, f(x) = 0. For example, the linear equation 2x - 4 = 0 can be written as y = 2x - 4. When this function is graphed, it has one x-intercept at x = 2, and that is the solution.

Graphing also works when two expressions are involved. For example, y₁ = x² and y₂ = 3x + 1 can be graphed on the same plane. The solutions are the x-coordinates where the two graphs intersect. These intersection points show where the expressions have the same value.

This method is useful because it gives a quick estimate without heavy algebra. It also makes the behavior of functions easier to see over a range of values. Intersections, turning points, and symmetry become visible on the graph. That makes it easier to compare equations and study trends, especially when exact answers are hard to find or when real-world data is modeled by functions.

Graphing Equations to Find Intercepts

coordinate plane

Finding Points on the Coordinate Plane

The Cartesian coordinate plane is used to find and plot points in two dimensions. It is made of two number lines that cross at right angles. The horizontal line is the x-axis, and the vertical line is the y-axis. Their meeting point is the origin, where both values are zero. The axes divide the plane into four quadrants. These quadrants are labeled in a counterclockwise direction, starting from the upper right. Every point on the plane is written as an ordered pair. The first number is the...

the distance formula

Finding Distance on a Coordinate Plane

Finding distance on a coordinate plane uses the distance formula and the Pythagorean Theorem. In geometry, this method helps measure the direct distance between two points on a flat plane. It is useful in many practical and theoretical settings. The formula comes from a right triangle. On a coordinate plane, the horizontal and vertical differences between two points become the legs of that triangle. The line connecting the points is the hypotenuse, and that is the shortest path between them. <br...

the midpoint formula

Finding the Center of a Line Segment

Finding the center of a line segment is a key idea in coordinate geometry. The midpoint is the point that lies exactly halfway between two points on a coordinate plane. It is used in mathematics, physics, engineering, and planning work where a central location matters. To work with a midpoint, start with two points, A(x1, y1) and B(x2, y2). A straight line segment can be drawn between them on the coordinate plane. The midpoint, labeled M, divides that segment into two equal parts. The...

graphs of equations in two variables

Plotting Two-Variable Equations with Tables

Plotting two-variable equations with tables helps show how x and y are related. An equation written as y = f(x) or Ax + By = C gives ordered pairs that satisfy the rule. Each pair can be checked by substituting the x and y values into the equation. A value table is a common way to build the graph. Start by choosing several values for the independent variable x. Then substitute each x value into the equation to find the matching y value. The results become ordered pairs on the Cartesian...

circles

Circle Equations in Standard Form

Circle equations in the coordinate plane use a center and a radius to describe every point on the curve. A circle is the set of all points that stay the same distance from a fixed point called the center. That constant distance is the radius. The distance formula connects a point x, y on the circle to the center h, k. The distance between those two points equals the radius r. When both sides of the distance formula are squared, the equation of the circle can be written in standard form. <br...

symmetry

Ellipse Symmetry at the Origin

An ellipse centered at the origin shows clear symmetry in its graph. Its equation describes a smooth, closed curve whose distance from the center keeps a constant ratio between the horizontal and vertical axes. Because the ellipse stretches farther along the x-axis than the y-axis, it has a horizontal shape. This ellipse has symmetry across the x-axis. That means the top half and bottom half are mirror images across the horizontal axis. Algebraically, the equation stays the same when y is...

solving equations graphically

Graphing equations helps students find intercepts and solutions on the coordinate plane. It gives a visual way to solve equations and understand how a function behaves. To use this method, write the equation in the form y = f(x). The solution to the original equation is the x-value where the graph crosses the x-axis. At that point, f(x) = 0. For example, the linear equation 2x - 4 = 0 can be written as y = 2x - 4. When this function is graphed, it has one x-intercept at x = 2, and that is the...

solving inequalities graphically

Graphing Inequality Solution Ranges

Graphing inequality solution ranges gives a visual way to find the x-values that make an inequality true. Students look at where a graph sits compared with the x-axis or with another graph. This shows the interval where the condition is satisfied. For a quadratic inequality, the first step is to plot the related function. For example, with x² − 4x + 2 &lt; 0, graph y = x² − 4x + 2. The solution is the set of x-values where the curve lies below the x-axis. Inequalities can also compare two...

key terms and concepts

Use graphs to solve equations by finding x-intercepts and graph intersections. Learn how y = f(x) reveals solutions, symmetry, and function behavior.

Graphing Equations to Find Intercepts | JoVE K12

The JoVE Math Fundamentals collection is designed to build a deep and comprehensive understanding of essential mathematics. Covering the foundations of algebra, geometry, trigonometry, and analytic reasoning, this course establishes a strong base for future studies. The collection connects core mathematical concepts with real-world practice, equipping learners to solve complex problems, master problem-solving skills, and apply abstract ideas.

math fundamentals

Graphing Equations to Find Intercepts

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