LINEAR INEQUALITIES — MATHS STD 11 Science — Question
Gujarat BoardEnglish MediumSTD 11 ScienceMATHSLINEAR INEQUALITIES2 Marks
Question
Find all pairs of consecutive odd natural number, both of which are larger than 10, such that their sum is less than 40.
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Answer
Let x be the smaller of the two consecutive odd natural numbers. Then the other odd integer is x+2. It is given that both the natural number are greater than 10 and their sum is less than 40. $\therefore$ x > 10 and, x + x + 2 < 40 $\Rightarrow$ x > 10 and 2x < 38 $\Rightarrow$ x > 10 and x <19 $\Rightarrow$ 10 < x < 19 $\Rightarrow$ x = 11,13,15,17 [$\because$ x is an odd number] Hence, the required pairs of odd natural number are (11, 13), (13, 15), (15, 17) and (17, 19).
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