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The roots of equation 6x2 − 5x + 1= 0 are 1/2 and 1/3. The sum of two numbers is 7 and the sum of their reciprocals is 7/12. Then smaller number is 3. - Mathematics

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Question

In the following question, two statements (i) and (ii) are given. Choose the valid statement.

  1. The roots of equation 6x2 − 5x + 1= 0 are `1/2 and 1/3.`
  2. The sum of two numbers is 7 and the sum of their reciprocals is `7/12`. Then smaller number is 3.

Options

  • Only (i)

  • Only (ii)

  • Both (i) and (ii)

  • Neither (i) nor (ii)

MCQ
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Solution

Both (i) and (ii)

Explanation:

Statement (i):

Given equation: 6x2 − 5x + 1 = 0

6x2 − 5x + 1 = (3x − 1) (2x − 1) = 0

`x = 1/3, 1/2`

Statement (i) is true.

Statement (ii):

Let the two numbers be aaa and b.

Given:

a + b = 7

`1/a + 1/b = 7/12`

`(a+b)/(ab) = 7/12`

`=> 7/(ab) = 7/12`

⇒ ab = 12

So the numbers satisfy:

x2 − 7x + 12 = 0

⇒ (x − 3) (x − 4) = 0

Numbers are 3 and 4.

Smaller number is 3.

Statement (ii) is true.

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Chapter 5: Quadratic equations - Exercise 5G [Page 95]

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Nootan Mathematics [English] Class 10 ICSE
Chapter 5 Quadratic equations
Exercise 5G | Q 4. | Page 95
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