Question

Question 23 Find all pairs of consecutive odd positive integers both of which are smaller than 10 such that their sum is more than 11.

Class X1 - Maths -Linear Inequalities Page 122

Answer 1

hope it helped uh....

Answer 2

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)