The sum of two numbers is 36. Their H.C.F. and L.C.M. are 3 and 105…

2016

The sum of two numbers is 36. Their H.C.F. and L.C.M. are 3 and 105 respectively. The sum of reciprocals of those two numbers will be

  1. A.

    1/3

  2. B.

    7/35

  3. C.

    4/35

  4. D.

    9/11

Attempted by 5 students.

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Correct answer: C

Let the two numbers be 3a and 3b, where a and b are co-prime (since H.C.F. is 3).

Given that their sum is 36:

3a + 3b = 36

Divide both sides by 3:

a + b = 12

Also, L.C.M. of the two numbers is 3ab = 105.

So, 3ab = 105 → ab = 35.

Now, we need to find the sum of reciprocals:

1/(3a) + 1/(3b) = (b + a)/(3ab)

Substitute a + b = 12 and ab = 35:

(12)/(3 × 35) = 12/105 = 4/35.

Therefore, the sum of reciprocals is 4/35.

हिन्दी उत्तर:

मान लीजिए दो संख्याएँ 3a और 3b हैं, जहाँ a और b सह-अभाज्य हैं (क्योंकि म.स. 3 है)।

दिया गया है कि उनका योग 36 है:

3a + 3b = 36

दोनों तरफ 3 से भाग देने पर:

a + b = 12

इसके अलावा, दोनों संख्याओं का ल.स. 3ab = 105 है।

तो, 3ab = 105 → ab = 35।

अब, हमें व्युत्क्रमों का योग ज्ञात करना है:

1/(3a) + 1/(3b) = (b + a)/(3ab)

a + b = 12 और ab = 35 का प्रतिस्थापन करने पर:

(12)/(3 × 35) = 12/105 = 4/35।

इसलिए, व्युत्क्रमों का योग 4/35 है।

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