SOLUTION: 2-logx=log5

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Question 1117302: 2-logx=log5
Found 3 solutions by josgarithmetic, MathTherapy, greenestamps:
Answer by josgarithmetic(39630) About Me  (Show Source):
Answer by MathTherapy(10557) About Me  (Show Source):
You can put this solution on YOUR website!

2-logx=log5
Correct way to do this:

2 - log x = log 5

2 = log 5 + log x

2 = log (5x)

matrix%281%2C3%2C+5x%2C+%22=%22%2C+10%5E2%29 ------- Converting to EXPONENTIAL form

5x = 100

highlight_green%28matrix%281%2C5%2C+x%2C+%22=%22%2C+100%2F5%2C+%22=%22%2C+20%29%29

Answer by greenestamps(13209) About Me  (Show Source):
You can put this solution on YOUR website!


There are MANY correct ways to work this problem.

I would definitely not use the method shown by tutor josgarithmetic, since it involves finding a numerical approximation of a logarithm.

The method shown by the other tutor is fine...

I would be inclined to rewrite the equation with every term as a logarithm and then use rules of logarithms:

2-log%2810%2Cx%29=log%2810%2C5%29
log%2810%2C100%29-log%2810%2Cx%29+=+log%2810%2C5%29
log%2810%2C100%2Fx%29+=+log%2810%2C5%29
100%2Fx+=+5
x+=+20