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1. the sum of the first n odd positive integers is 64. what is the value of n ?

2. how many positive integers between 100 and 200 are divisible by 14 ?


please please help :(

1 Answer

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  • The value of the n is 8.
  • There are 7 positive integers between 100 and 200 which are divisible by 14.

Explanation:

The sum of first n odd positive integer is n^2. The nth odd number is 2n-1.

i.e. 1 + 3 + ........+ (2n-1) = n^2.

1 + 3 +..........+ (2n-1) = 64

n^2 = 64

n = 8.

The positive integers between 100 and 200 which are divisible by 14 are 112, 126, 140, 154, 168, 182, 196. It is obtained by the multiples of 14 between 100 and 200.

100 = 7 * 14 + 2

200 = 14 * 14 + 4. The answer is 14 - 7 = 7

The seven numbers are

14 * 8 = 112

14 * 9 = 126

14 * 10 = 140

14 * 11 = 154

14 * 12 = 168

14 * 13 = 182

14 * 14 = 196

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