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प्रश्न
If m = log 20 and n = log 25, find the value of x, so that :
2 log (x - 4) = 2 m - n.
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उत्तर
Given that
m = log 20 and n = log 25
We also have
2log( x - 4 ) = 2m - n
⇒ 2log ( x - 4 ) = 2log 20 - log 25
⇒ log( x - 4 )2 = log202 - log 25
⇒ log( x - 4 )2 = log 400 - log 25
⇒ log( x - 4 )2 = log `400/25`
⇒ ( x - 4 )2 = `400/25`
⇒ ( x - 4 )2 = 16
⇒ x - 4 = 4
⇒ x = 4 + 4
⇒ x = 8.
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