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Question
Find x, if : log7 (2x2 - 1) = 2
Sum
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Solution
Consider the equation
log7( 2x2 - 1 ) = 2
⇒ 72 = 2x2 - 1
⇒ 7 x 7 = 2x2 - 1
⇒ 2x2 - 1 - 49 = 0
⇒ 2x2 - 50 = 0
⇒ 2x2 = 50
⇒ x2 = `50/2`
⇒ x2 = 25
⇒ x = `+-sqrt25`
⇒ x = 5 .....[ neglecting the negative value ]
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Interchanging Logarithmic and Exponential Forms
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