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Mind Map: Rational Numbers | Mathematics (Maths) Class 8

The document Mind Map: Rational Numbers | Mathematics (Maths) Class 8 is a part of the Class 8 Course Mathematics (Maths) Class 8.
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FAQs on Mind Map: Rational Numbers - Mathematics (Maths) Class 8

1. What are rational numbers, and how are they different from integers and whole numbers?
Ans. Rational numbers are numbers that can be expressed as a fraction p/q, where p and q are integers, and q is not equal to zero. They include integers (which are whole numbers that can be positive, negative, or zero) as well as fractions. Whole numbers are a subset of rational numbers that include all non-negative integers (0, 1, 2, ...). Thus, while all integers and whole numbers are rational numbers, not all rational numbers are integers or whole numbers.
2. How do you convert a repeating decimal into a rational number?
Ans. To convert a repeating decimal into a rational number, let x be the repeating decimal. For example, if x = 0.666... (where 6 repeats), multiply both sides by 10 (to shift the decimal point) to get 10x = 6. Then, subtract the original equation from this new equation: 10x - x = 6, which simplifies to 9x = 6. Dividing both sides by 9 gives x = 6/9, which can be simplified to 2/3. Thus, 0.666... = 2/3 as a rational number.
3. What is the significance of the term "like" and "unlike" fractions in rational numbers?
Ans. "Like fractions" are fractions that have the same denominator, making them easy to compare and perform arithmetic operations like addition and subtraction. For example, 1/4 and 3/4 are like fractions. "Unlike fractions," on the other hand, have different denominators, which require finding a common denominator before performing operations. For instance, to add 1/3 and 1/4, you would first convert them to like fractions (common denominator of 12) to get 4/12 + 3/12 = 7/12.
4. How do you perform operations such as addition and subtraction on rational numbers?
Ans. To add or subtract rational numbers, first ensure they have a common denominator. For instance, to add 1/3 and 1/4, find a common denominator (12), converting the fractions to 4/12 and 3/12, respectively. Then, add the numerators: 4 + 3 = 7, resulting in 7/12. For subtraction, the process is the same, but you subtract the numerators instead. So, 5/6 - 1/3 would require converting 1/3 to 2/6, yielding 5/6 - 2/6 = 3/6, which simplifies to 1/2.
5. What are some real-life examples of rational numbers?
Ans. Rational numbers are prevalent in everyday life. For example, when measuring ingredients in cooking, such as 1/2 cup of sugar or 3/4 teaspoon of salt, these quantities are rational numbers. Similarly, when dealing with money, prices such as $4.50 or $2.75 represent rational numbers as they can be expressed as fractions (9/2 and 11/4, respectively). Additionally, in sports, scores and statistics often involve rational numbers, like a batting average of 0.250 or a completion percentage of 75/100.
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