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Question -

If Zeba were younger by 5 years than what she really is, then the square of her age (in years) would have been 11 more than 5 times her actual age. What is her age now? [NCERT Exemplar]



Answer -

Let the actual age of Zeba = x year .
Her age when she was 5 years younger = (x тАУ 5) years
Now, by given condition,
Square of her age = 11 more than 5 times her actual age
(x тАУ 5)┬▓ = 5 x actual age + 11
=> (x тАУ 5)┬▓ = 5x + 11
=> x┬▓ + 25 тАУ 10x = 5x + 11
=> x┬▓ тАУ 15x + 14 = 0
=> x┬▓ тАУ 14x тАУ x + 14 = 0 [by splitting the middle term]
=> x (x тАУ 14) тАУ 1 (x тАУ 14) = 0
=> (x тАУ 1) (x тАУ 14) = 0
=> x = 14
[Here, x тЙа 1 because her age is x тАУ 5. So, x тАУ 5 = 1 тАУ 5= -4 i.e., age cannot be negative]
Hence, required ZebaтАЩs age now is 14 years.

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