Question

3.Find all pairs of consecutive odd positive integers, both of which are smaller than 18, such that their sum is more than 20.

Answer 1

Answer:

Step-by-step explanation:

Here is an example for your question:-

Q) Find all pairs of consecutive odd positive integers both of which are smaller than 10 such that their sum is more than 11.

A) Let the two consecutive odd positive integer be x and x+2.

Both number are smaller than 10 Therefore

x+2<10

Adding −2 to both sides,

=>x<10−2

=>x<8

Also sum of the two integers is more than 11.

So, x+x+2>11

=>2x+2>11

adding −2 to both sides,

=>2x>11−2

=>2x>9

Diving by 2 on both sides,

=>x>9/2

=>x>4.5

Step 2 :

Since x is an odd integer number greater than 4.5 and less than 8 (from 0) x can take values 5 and 7.

Thus the required pairs are (5,7) and (7,9)