log (x + 3) log (x + 5) = log 35, solve for x :

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NIELIT Scientific Assistant CS 5 Dec 2021 Official Paper
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Answer (Detailed Solution Below)

Option 2 : 2
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Given:

log (x + 3) log (x + 5) = log 35

Formula used:

log(a) log(b) = log(c)

Calculation:

log (x + 3) log (x + 5) = log 35

⇒ log (x + 3) log (x + 5) = log 5 × log 7

⇒ (x + 3) (x + 5) = 35

⇒ x2 + 8x + 15 = 35

⇒ x2 + 8x - 20 = 0

⇒ (x + 10)(x - 2) = 0

⇒ x = -10 or x = 2

Since x must be positive, x = 2

∴ The correct answer is option (2).

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Last updated on Jun 12, 2025

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-> The NIELIT Scientific Assistant 2025 Notification has been released by the National Institute of Electronics and Information Technology (NIELIT).

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