📚 Year 9 SQA Maths: Key Terms and Glossary Quick Reference Guide | Year 9 SQA 数学：词汇术语速记指南
Mastering the language of mathematics is the first step to success in your SQA Year 9 course. This quick reference guide covers essential terms you will encounter across all topics, presented in clear English and Chinese explanations to help you learn, recall, and use them with confidence. Use this as your pocket dictionary for homework, revision, and classroom discussion.
掌握数学语言是在 SQA Year 9 课程中取得成功的第一步。本速记指南涵盖了你将在所有主题中遇到的基本术语，用清晰的英文和中文解释呈现，帮助你学习、记忆并自信地运用它们。请把这份资料当作你完成作业、复习备考和课堂讨论的随身词典。
1. Algebraic Expressions | 代数表达式
A variable is a symbol, usually a letter, that represents an unknown number or a number that can change. In the expression 3x + 5, x is the variable.
变量是一个符号，通常是字母，代表一个未知数或可以变化的数。在表达式 3x + 5 中，x 就是变量。
A coefficient is the number multiplied by a variable. For example, in 4y, the coefficient is 4; in -2a, the coefficient is -2.
系数是乘以变量的数字。例如，在 4y 中，系数是 4；在 -2a 中，系数是 -2。
A term is a single mathematical entity that can be a number, a variable, or numbers and variables multiplied together. Expressions like 7, 2ab, or -3x² are all terms.
项是一个单一的数学对象，可以是一个数、一个变量，或者数字与变量的乘积。像 7、2ab 或 -3x² 这样的式子都是项。
Like terms have exactly the same variable part raised to the same power. For instance, 5x and -3x are like terms, while 4x² and 4x are not.
同类项具有完全相同的变量部分且指数相同。例如，5x 和 -3x 是同类项，而 4x² 和 4x 则不是。
2. Equations and Inequalities | 方程与不等式
An equation the value of the variable that makes the statement true. 2x + 1 = 7 is a linear equation.
方程表示两个表达式相等，使用等号 =。解方程意味着找到使等式成立的变量的值。2x + 1 = 7 是一个一元一次方程。
A solution e value of the variable that satisfies the equation. For x + 3 = 8, the solution is x = 5.
解（或根）是满足方程的变量的值。对于 x + 3 = 8，其解为 x = 5。
An inequality ual to), or ≥ (greater than or equal to). The inequality 3y > 9 means y is greater than 3.
不等式使用 <（小于）、>（大于）、≤（小于或等于）或 ≥（大于或等于）等符号来比较两个表达式。不等式 3y > 9 表示 y 大于 3。
The balance method is a common technique for solving equations. You must perform the same operation on both sides to keep the equation balanced.
天平法是解方程的常用技巧。你必须在等号两边同时进行相同的运算，以保持等式平衡。
3. Number System | 数系
Integers are the set of whole numbers and their negatives: …, -3, -2, -1, 0, 1, 2, 3, … They do not include fractions or decimals.
整数是所有正整数、负整数和零的集合：…, -3, -2, -1, 0, 1, 2, 3, … 它们不包括分数或小数。
A rational number can be expressed as a fraction p/q, where p and q are integers and q ≠ 0. Every terminating or recurring decimal is a rational number.
有理数是可以表示为分数 p/q 的数，其中 p 和 q 是整数且 q ≠ 0。每个有限小数或循环小数都是有理数。
An irrational number cannot be written as a simple fraction; its decimal representation goes on forever without repeating. Examples include √2 and π.
无理数不能写成分数形式；它的小数部分无限不循环。例如 √2 和 π。
The place value of a digit depends on its position in a number. In 5407, the digit 5 has a place value of thousands, meaning 5000.
数字的位值取决于它在数中的位置。在 5407 中，数字 5 的位值是千位，即 5000。
4. Fractions, Decimals and Percentages | 分数、小数与百分比
A fraction represents a part of a whole. It has a numerator (top number) and a denominator (bottom number). In 3/4, the numerator 3 shows how many parts we have, and the denominator 4 shows the total number of equal parts.
分数表示整体的一部分。它有分子（上面的数）和分母（下面的数）。在 3/4 中，分子 3 表示我们拥有几份，分母 4 表示整体被分成多少等份。
Equivalent fractions fractions by multiplying or dividing the numerator and denominator by the same non-zero number.
等值分数表示相同的值。例如，1/2 = 2/4 = 3/6。你可以通过将分子和分母同时乘以或除以同一个非零数来得到等值分数。
Percentages are fractions with a denominator of 100. The symbol % means 'per hundred'. 45% is equivalent to 45/100 or 0.45 as a decimal.
百分比是分母为 100 的分数。符号 % 表示“每百分之”。45% 相当于 45/100 或小数 0.45。
To convert a fraction to a decimal, divide the numerator by the denominator. To convert a decimal to a percentage, multiply by 100 and add the % sign.
要将分数转换为小数，用分子除以分母。要将小数转换为百分比，乘以 100 并加上 % 符号。
5. Ratio, Proportion and Rates | 比、比例与速率
A ratio compares the sizes of two or more quantities in the same unit. The ratio a : b is read 'a to b'. For example, if a fruit bowl has 3 apples and 2 oranges, the ratio of apples to oranges is 3 : 2.
比用于比较同一单位下两个或多个量的大小。比 a : b 读作“a 比 b”。例如，如果一只水果碗里有 3 个苹果和 2 个橙子，苹果与橙子的比就是 3 : 2。
Direct proportion means that as one quantity increases, the other increases at the same rate. The graph of a directly proportional relationship is a straight line through the origin.
正比例意味着当一个量增大时，另一个量以相同的速率增大。成正比例关系的图像是一条经过原点的直线。
A rate is a special ratio that compares quantities of different units, such as miles per hour (mph) or price per kilogram (£/kg).
速率是一种特殊的比，用于比较不同单位的量，例如每小时英里数（英里/小时）或每千克价格（英镑/千克）。
The unitary method involves finding the value of one unit first and then scaling up or down to find the required value. It is very useful for solving proportion problems.
单位法是先求出一个单位的对应值，然后按比例放大或缩小以求得所需值。它在解决比例问题时非常实用。
6. Geometry: Angles and Shapes | 几何：角与图形
An acute angle measures between 0° and 90°. A right angle is exactly 90°. An obtuse angle lies between 90° and 180°. A reflex angle measures between 180° and 360°.
锐角大于 0° 且小于 90°。直角正好是 90°。钝角大于 90° 且小于 180°。优角大于 180° 且小于 360°。
Complementary angles are two angles whose sum is 90°. Supplementary angles sum to 180°.
余角是两个角之和为 90°。补角是两个角之和为 180°。
A polygon is a closed plane figure with straight sides. A regular polygon has all sides and all angles equal. Common polygons include triangles (3 sides), quadrilaterals (4 sides), pentagons (5), and hexagons (6).
多边形是由直线段围成的封闭平面图形。正多边形的所有边和所有角都相等。常见的多边形有三角形（3 条边）、四边形（4 条边）、五边形（5）和六边形（6）。
The sum of interior angles sides is (n - 2) × 180°. For a quadrilateral, n = 4, giving an interior angle sum of 360°.
有 n 条边的多边形，其内角和为 (n - 2) × 180°。对于四边形，n = 4，内角和为 360°。
7. Perimeter, Area and Volume | 周长、面积与体积
Perimeter ape. To find the perimeter of a rectangle, add the lengths of all four sides: P = 2l + 2w.
周长是一个二维图形外边线的总长度。要计算长方形的周长，将四条边的长度相加：P = 2l + 2w。
Area ulas include: Area of a rectangle = base × height; Area of a triangle = ½ × base × height.
面积衡量一个图形所覆盖的表面大小。常用公式包括：长方形面积 = 底 × 高；三角形面积 = ½ × 底 × 高。
Volume a cuboid is length × width × height. For a prism, volume = area of cross-section × length.
体积衡量一个三维立体内部的空间大小。长方体的体积是 长 × 宽 × 高。对于棱柱，体积 = 底面积 × 高。
Surface area he is the total area of all faces of a 3D solid. For a cube of side length s, surface area = 6s².
表面积是一个三维立体所有面的总面积。边长为 s 的正方体，表面积 = 6s²。
8. Coordinates and Graphs | 坐标与图形
The Cartesian coordinate system uses two perpendicular number lines: the x-axis (horizontal) and the y-axis (vertical). A point is located by an ordered pair (x, y).
笛卡尔坐标系使用两条互相垂直的数轴：x 轴（水平）和 y 轴（垂直）。一个点用有序数对 (x, y) 来定位。
The origin is the point (0, 0) where the two axes cross. The plane is divided into four quadrants.
原点是坐标轴的交叉点 (0, 0)。坐标平面被分为四个象限。
A linear graph s equation can be written as y = mx + c, where m is the gradient and c is the y-intercept.
线性图表示变化率恒定的关系。它的方程可以写成 y = mx + c 的形式，其中 m 是斜率，c 是 y 轴截距。
The gradient ess. It is calculated as vertical change divided by horizontal change: gradient = Δy / Δx.
一条直线的斜率衡量它的倾斜度。其计算公式为纵向变化除以横向变化：斜率 = Δy / Δx。
9. Statistics | 统计
The mean is the average of a data set. It is calculated by summing all values and dividing by the number of values.
平均数（均值）是一组数据的平均值。计算方法是将所有数值相加，再除以数值的个数。
The median is the middle value when data is arranged in order. For an even number of data points, the median is the mean of the two middle numbers.
中位数是将数据从小到大排序后处于中间位置的值。如果数据个数为偶数，中位数就是中间两个数的平均数。
The mode is the value that appears most frequently in a data set. A set may have one mode, more than one mode, or no mode at all.
众数是一组数据中出现频率最高的值。一组数据可能有一个众数、多个众数，或者没有众数。
The range measures the spread of data and is the difference between the largest and smallest values. Range = maximum value - minimum value.
极差衡量数据的离散程度，它是最大值与最小值的差。极差 = 最大值 - 最小值。
10. Probability | 概率
Probability is a measure of how likely an event is to happen, expressed as a number between 0 (impossible) and 1 (certain). You can also write it as a fraction, decimal, or percentage.
概率是衡量一个事件发生可能性的数值，介于 0（不可能）和 1（必然）之间。你也可以用分数、小数或百分比来表示。
A sample space is the set of all possible outcomes. When tossing a fair coin, the sample space is {Head, Tail}.
样本空间是所有可能结果的集合。在抛一枚质地均匀的硬币时，样本空间是 {正面，反面}。
The probability of an event f favourable outcomes / total number of possible outcomes, provided all outcomes are equally likely.
事件的概率公式为：P(事件) = 有利结果数 / 所有可能结果总数，前提是每个结果发生的可能性相等。
Mutually exclusive events cannot happen at the same time. The probability of either event A or event B occurring is P(A) + P(B).
互斥事件不可能同时发生。事件 A 或事件 B 发生的概率为 P(A) + P(B)。
Published by TutorHao | Mathematics Revision Series | aleveler.com
更多咨询请联系16621398022（同微信）
或截图后用「扫一扫 → 相册」选择本图