SOLUTION: Hi, what is the log of log7 50= Sorry, I am not sure how to make the 7 a subscript. I understand I am trying to find the exponent of 7 that will produce 50. 7 squared is 49,

Algebra ->  Test -> SOLUTION: Hi, what is the log of log7 50= Sorry, I am not sure how to make the 7 a subscript. I understand I am trying to find the exponent of 7 that will produce 50. 7 squared is 49,      Log On


   



Question 295955: Hi, what is the log of log7 50=
Sorry, I am not sure how to make the 7 a subscript.
I understand I am trying to find the exponent of 7 that will produce 50.
7 squared is 49, so what do I do from there?


Thanking You in Advance,
Jacinta













Answer by Theo(13342) About Me  (Show Source):
You can put this solution on YOUR website!
Your equation is:

log%287%2C50%29+=+y

This is true, if and only if 7%5Ey+=+50

Take the log of both sides of this equation to get:

this log you are taking is to the base 10 which is the LOG function of your calculator.

log%2810%2C7%5Ey%29+=+log%2810%2C50%29

Since, in general, log%28x%5Ey%29+=+y%2Alog%28x%29, this equation becomes:

y%2Alog%2810%2C7%29+=+log%2810%2C50%29

Divide both sides of this equation by log%2810%2C7%29 to get:

y+=+log%2810%2C50%29%2Flog%2810%2C7%29 *****

***** This equation is the log base conversion formula described below.




Use your calculator to get log of 50 divided by log of 10 to get:

y+=+1.698970004%2F.84509804 which becomes:

y+=+2.010382138

That's your answer:

Plug into your original equation to get:

log%287%2C50%29+=+y becomes:

log%287%2C50%29+=+2.010382138

this is true if and only if:

7%5E2.010382138+=+50

Use your calculator to determine that 7%5E2.010382138 = 50, confirming that the answer of y = 2.010382138 is good.

You needed to know that, in general:

log%28b%2Cx%29+=+y if and only if b%5Ey+=+x

There is also a log base conversion formula that will provide you with the same answer.

That conversion formula is:

y = log%28b%2Cx%29+=+log%28c%2Cx%29+%2F+log%28c%2Cb%29

In your case, this conversion formula would work like this:

y = log%287%2C50%29+=+log%2810%2C50%29+%2F+log%2810%2C7%29

If you look at what we did earlier, you will see that our solution yielded this exact formula.

That would be the equation denoted with ***** up above.

That equation was y+=+log%2810%2C50%29%2Flog%2810%2C7%29

Our conversion equation here is:

y = log%287%2C50%29+=+log%2810%2C50%29+%2F+log%2810%2C7%29

y = log%287%2C50%29 is your original equation.

y = log%2810%2C50%29+%2F+log%2810%2C7%29 is the conversion equation.