log 5  (3x)  - log 5 (15) = 1  solve for x

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hala718's profile pic

hala718 | High School Teacher | (Level 1) Educator Emeritus

Posted on

log 5 (3x) - log 5 (15) = 1

We know that log a - log b = log (a/b)

==> log 5 (3x/15) = 1

==> log 5 (x/5) = 1\

But log 5 (5) = 1

==> log 5 (x/5) = log 5 (5)

==> X/5 = 5

==> X = 25

krishna-agrawala's profile pic

krishna-agrawala | College Teacher | (Level 3) Valedictorian

Posted on

Given:

log5 (3x) - log5 (15) = 1

Applying the formula:

log a - log b = log (a/b)

the above equation becomes:

log5 (3x/15) = 1

==> log5 (x/5) = 1

We know:

log5 (5) = 1

Therefore:

og5 (x/5) = log5 (5)

Therefore:

x/5 = 5

==> x = 5*5 = 25

Answer:

x = 25

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