Grade 8 Maths Practice Workbook | 八年级数学练习册

2026-08-22 01:14 · 本文部分内容由AI辅助创作

📚 Grade 8 Maths Practice Workbook | 八年级数学练习册

This Grade 8 Maths Practice Workbook covers the essential skills needed for Grade 8 mathematics. Each section includes concise explanations, worked examples and practice questions to help you master the topic step by step.

本八年级数学练习册涵盖八年级数学所需的各项核心技能。每个部分都包含简明讲解、典型例题和练习题，帮助你逐步掌握知识点。

1. Integers and Rational Numbers | 整数与有理数

moving left decreases value. The absolute value of a number is its distance from zero, so |−7| = 7 and |5| = 5.

整数包括正整数、负整数和零。在数轴上，向右移动数值增大，向左移动数值减小。一个数的绝对值是它到零的距离，因此 |−7| = 7，|5| = 5。

Rational numbers can be written as a fraction a/b where b ≠ 0. To add or subtract rational numbers with different denominators, first find the lowest common denominator. For multiplication, multiply numerators and denominators separately; for division, multiply by the reciprocal.

有理数可以写成 a/b 的分数形式，其中 b ≠ 0。不同分母的有理数相加减时，先找最小公分母。乘法时分子分母分别相乘；除法时乘以倒数。

Example: −3 + 8 = 5, −12 ÷ (−4) = 3, and 2/3 × 9/4 = 18/12 = 3/2.

例如：−3 + 8 = 5，−12 ÷ (−4) = 3，2/3 × 9/4 = 18/12 = 3/2。

2. Laws of Exponents and Scientific Notation | 指数律与科学记数法

ᵐ ÷ aⁿ = aᵐ⁻ⁿ. When raising a power to another power, multiply the exponents: (aᵐ)ⁿ = aᵐⁿ.

同底数幂相乘时，指数相加：aᵐ × aⁿ = aᵐ⁺ⁿ。同底数幂相除时，指数相减：aᵐ ÷ aⁿ = aᵐ⁻ⁿ。幂的乘方时，指数相乘：(aᵐ)ⁿ = aᵐⁿ。

umber as a × 10ᵏ, where 1 ≤ a < 10 and k is an integer. For example, 0.00042 = 4.2 × 10⁻⁴.

负指数表示倒数：a⁻ⁿ = 1/aⁿ。科学记数法把数字写成 a × 10ᵏ，其中 1 ≤ a < 10，k 为整数。例如 0.00042 = 4.2 × 10⁻⁴。

3. Ratios, Proportions and Percentages | 比、比例与百分数

total number of parts (2 + 3 = 5), then multiply the quantity by 2/5 and 3/5 respectively.

比用来比较两个量。按 2 : 3 分配一个量时，先求总份数（2 + 3 = 5），再分别乘以 2/5 和 3/5。

Percentage increase or decrease is calculated as (change ÷ original amount) × 100% To find a percentage of an amount, convert the percentage to a decimal and then multiply.

百分比增加或减少的计算公式为（变化量 ÷ 原量）× 100%。求一个数的百分之几时，先把百分数转化为小数再相乘。

Example: A jacket costing $80 is reduced by 15%. The discount is 0.15 × 80 = $12, so the new price is 80 − 12 = $68.

例如：一件夹克原价 80 美元，降价 15%。折扣为 0.15 × 80 = 12 美元，因此新价格为 80 − 12 = 68 美元。

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