हिंदी

The product of Tanvy’s age (in years) 5 years ago and her age is 8 years later is 30. Find her present age.

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प्रश्न

The product of Tanvy’s age (in years) 5 years ago and her age is 8 years later is 30. Find her present age.

योग
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उत्तर

Let the present age of Meena be x years.

According to the question: 

(x – 5) (x + 8) = 30 

⇒ x2 + 3x – 40 = 30 

⇒ x2 + 3x – 70 = 0 

⇒ x2 + (10 – 7)x – 70 = 0

⇒ x2 + 10x – 7x – 70 = 0 

⇒ x(x + 10) – 7(x + 10) = 0 

⇒ (x + 10)(x – 7) = 0 

⇒ x + 10 = 0 or x – 7 = 0 

⇒ x = –10 or x = 7 

⇒ x = 7   ...(∴ Age cannot be negative)

Thus, the present age of Meena is 7 years. 

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अध्याय 4: Quadratic Equations - EXERCISE 4D [पृष्ठ २२६]

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आर.एस. अग्रवाल Mathematics [English] Class 10
अध्याय 4 Quadratic Equations
EXERCISE 4D | Q 41. | पृष्ठ २२६
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