Question

Q7.) The elements of set A, satisfy the property n/(2n+1), neN ,n <5 for their
elements. The element which does not belong to the set
3/7
O 4/9
O 1/3
5/11​

Answer 1

Answer:

The given sets are:

A={x:x∈N}={1,2,3,4.....}

B={x:x=2n,n∈N}={2,4,6,8,10....}

C={x:x=2n−1,n∈N}={1,3,5,7,9.......}

D={x:x is a prime number}={2,3,5,7,11,13....}

∴ A∩B={1,2,3,4....}∩{2,4,6,8....}

={2,4,6,8....}

=B

Hence

A∩B=B

Answer

Answer 2

Answer:

$\frac{5}{11}$ is the element which does not belong to the set A.

Step-by-step explanation:

Roaster form: Listing the elements of the set, separated by commas and inside a set of curly brackets is known as roaster form.

Given: Set A = { $\frac{n}{2n+1}$ , n ∈ $N$ and n < 5}

Observe that the set A contains only 4 elements as n < 5, i.e.,

For n = 1,

$\frac{1}{2(1)+1}$

⇒ $\frac{1}{3}$

For n = 2,

$\frac{2}{2(2)+1}$

⇒ $\frac{2}{4+1}$

⇒ $\frac{2}{5}$

For n = 3,

$\frac{3}{2(3)+1}$

⇒ $\frac{3}{6+1}$

⇒ $\frac{3}{7}$

For n = 4,

$\frac{4}{2(4)+1}$

⇒ $\frac{4}{8+1}$

⇒ $\frac{4}{9}$

Write the set in the roaster form as follows:

A = { $\frac{1}{3}, \frac{2}{5} ,\frac{3}{7}, \frac{4}{9}$}

(a) Clearly $\frac{3}{7}$ ∈ A.

(b) Clearly $\frac{4}{9}$ ∈ A.

(c) Clearly $\frac{1}{3}$ ∈ A.

(d) As $\frac{5}{11}$ ∉ A.

Therefore, $\frac{5}{11}$ is the element which does not belong to the set A.

SPJ3