Download RS Aggarwal Solutions Class 7 Chapter-4 Rational Numbers (Exercise 4B) Exercise 4.2 - Free PDF
FAQs on RS Aggarwal Solutions Class 7 Chapter - 4 Rational Numbers (Exercise 4B) Exercise 4.2: Download Free PDF
1. How do you correctly identify and express a rational number in its standard form as required in RS Aggarwal Class 7, Exercise 4B?
To solve problems in Exercise 4B, first ensure the number can be written as p/q where q is not zero. For its standard form, the denominator 'q' must be positive, and the only common factor between the numerator 'p' and the denominator 'q' should be 1. For example, to express 33/-44 in standard form, first make the denominator positive: -33/44. Then, divide both by their greatest common divisor (11) to get -3/4.
2. What is the step-by-step method to determine if a rational number is positive or negative before representing it on a number line?
A rational number is positive if both its numerator and denominator have the same sign (e.g., 5/7 or -5/-7). It is negative if they have opposite signs (e.g., -5/7 or 5/-7). Before plotting on a number line as in Exercise 4B, simplify it to its standard form. A positive number will be on the right of zero, and a negative number will be on the left.
3. What are the precise steps to represent a rational number like 5/3 on a number line?
To represent a rational number like 5/3 on a number line, follow these steps:
- Check if it's positive or negative. Since 5/3 is positive, it lies to the right of 0.
- Identify the two integers it lies between. 5/3 is equal to 1 and 2/3, so it lies between 1 and 2.
- Divide the segment between 1 and 2 into three equal parts (as the denominator is 3).
- The second mark after 1 represents the point 5/3.
4. Why is converting a rational number to its standard form a crucial first step before comparing or plotting it?
Converting a rational number to its standard form is crucial because it provides a unique and simplified representation. For instance, 2/3, 4/6, and 8/12 all represent the same value, but 2/3 is the standard form. Using this form prevents confusion and errors when comparing magnitudes (e.g., which is greater?) or locating the precise point on a number line. It ensures consistency in your solutions.
5. How does finding a common denominator help in comparing two different rational numbers like 3/4 and 5/6?
Finding a common denominator transforms fractions into equivalent ones that can be compared directly by their numerators. For 3/4 and 5/6, the least common multiple of 4 and 6 is 12.
- 3/4 becomes (3×3)/(4×3) = 9/12.
- 5/6 becomes (5×2)/(6×2) = 10/12.
6. What is a common mistake when comparing two negative rational numbers, for example, -2/3 and -4/5?
A common mistake is to assume the number with the larger-looking numerator is greater, which is incorrect for negative numbers. The correct method is to first find a common denominator (15):
- -2/3 becomes -10/15.
- -4/5 becomes -12/15.











