Question

2. Find all pairs of consecutive odd positive integers, both
of which are smaller than 10 such that their sum is more
than 11.
(N.C.E.R.T:)​

Answer 1

Let 2x+1 and 2x +3 are two positive odd integers .

a/C to question ,

2x +1 < 10

=> 2x < 10-1 = 9

=> 2x < 9

x < 9/2

and 2x + 3 < 10

=> 2x < 7

x < 7/2

and sum of (2x+1) and (2x +3) >11

2x +1 + 2x +3 > 11

4x +4 > 11

4x > 7

x > 7/4

now, plotting all these values on number line . (see attachment)

a/C to attachment ,

7/4 < x < 7/2

hence, possible value of x = 2, 3

when x = 2 then, (2×2+1,2×2+3)= (5, 7)

when x = 3 then, (2×3+1,2×3+3) = (7,9)

Answer 2

Answer:

pairs are 5&7,,7&9. this is correct answer