Class 7 Mathematics — Chapter 4: EXPRESSIONS USING LETTER-NUMBERS

What you'll learn

• ▸Using Letters to Represent Numbers (Variables)
• ▸Understanding Algebraic Expressions
• ▸Forming Expressions from Word Problems
• ▸Evaluating Expressions by Substitution
• ▸Translating Verbal Phrases to Expressions
• ▸Algebraic Notation for Multiplication
• ▸Expressions as Formulas
• ▸Revisiting Order of Operations
• ▸Describing Situations for Given Expressions

Chapter Summary

--- PAGE 1 --- 4 EXPRESSIONS USING LETTER- NUMBERS 0774CH04 4.1 The Notion of Letter-Numbers In this chapter we shall look at a concise way of expressing mathematical relations and patterns. We shall see how this helps us in thinking about these relationships and patterns, and in explaining why they may hold true. ? Example 1: Shabnam is 3 years older than Aftab. When Aftab's age is 10 years, Shabnam's age will be 13 years. Now Aftab's age is 18 years, what will Shabnam's age be? _____ ? Given Aftab's age, how will you find out Shabnam's age? Easy: We add 3 to Aftab's age to get Shabnam's age. ? Can we write this as an expression? Shabnam's age is 3 years more than Aftab's. In short, this can be written as: Shabnam's age = Aftab's age + 3. Such mathematical relations are generally represented in a shorthand form. In the relation above, instead of writing the phrase 'Aftab's Age', the convention is to use a convenient symbol. Usually, letters o…

Practice Questions from this Chapter

Tap "Get Solution" on any question to ask our AI tutor.

1. Explain algebraic expressions simply? Get Solution →
2. Show real-world variable examples? Get Solution →
3. Create new math patterns? Get Solution →
4. According to the text, what are letters like 'a' and 's' called when they are used to represent numbers in mathematical expressions? Get Solution →
5. What is a mathematical expression containing letter-numbers, such as 'a + 3', called? Get Solution →
6. As a standard practice in algebra, how is the expression '4 × n' typically shortened? Get Solution →
7. In the example where Shabnam is 3 years older than Aftab, if Aftab's age is represented by the letter 'a', what is the expression for Shabnam's age? Get Solution →
8. The text states that mathematical relations expressed with letter-numbers, such as the formula for a perimeter, are often called what? Get Solution →

Did you know?

• 💡 The word algebra comes from an Arabic term meaning the reunion of broken parts.
• 💡 Ancient Egyptians used pictures called hieroglyphs to represent unknown values in math.
• 💡 The equals sign "=" was invented in 1557 to avoid writing "is equal to."
• 💡 The letter "x" became the most common unknown variable thanks to René Descartes.
• 💡 Even simple cooking recipes follow a precise mathematical formula for ingredients and steps.

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