Question

Write the set {x:x is a positive integer and x2 <40} in the roster form .

Answer 1

Answer:

1,2,3,4,5,6

Step-by-step explanation:

1^2=1<40

2^2=4<40

3^2=9<40

4^2=16<40

5^2=25<40

6^2=36<40

7^2=49>40

Hence, required set is (1,2,3,4,5,6)

Answer 2

The required set = {1, 2, 3, 4, 5, 6}

Given:

The set = {x:x is a positive integer and x² <40}

To find:

Write the set in the roster form

Solution:

Given that x is element of given set where x is positive integer

and x² < 40

Now find for what values of x, x² will be less than 40

We can find it by trial and error method as shown below

Take x = 1 ⇒ x² = 1² = 1 < 40

Take x = 2 ⇒ x² = 2² = 4 < 40

Take x = 3 ⇒ x² = 3² = 9 < 40

Take x = 4 ⇒ x² = 4² = 16 < 40

Take x = 5 ⇒ x² = 5² = 25 < 40

Take x = 6 ⇒ x² = 6² = 36 < 40

So the required set = {1, 2, 3, 4, 5, 6}

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