Question

use the change of base formula to evaluate log2 74
can someone explain

Answer 1

Are you allowed to use a calculator for this one lilman?

Answer 2

Yes but i have the ti30x and not sure how to use it

Answer 3

Ok so we want to convert the logs to either base 10 or base e, those are the ones that your calculator can handle.

Change of Base Formula:\[\huge \log_a b=\frac{\log_{10}b}{\log_{10}a}\]

Answer 4

Using the rule this is what we get,
\[\huge \log_2 74=\frac{\log_{10}74}{\log_{10}2}\]
Understand how I rewrote that?

Answer 5

yea, but not sure how to use the calculator

Answer 6

Ok calculators can be somewhat confusing.. getting experience with your calculator is important.

I would highly recommend getting familiar with the "previous answer" button. You're less prone to make a mistake than if you were to write a ton of parentheses.

I'm using a TI-34II
It's probably similar, so let's see if we can figure this out.

Answer 7

ok i also have a ti84 and have never figured it out

Answer 8

If you go into higher level math classes, they often won't allow you to use graphing calculators. So it's a good idea to get used to the ole ti30x. :)

Hmm so where to get started.
Are you using a ti30xs, ti30xa, ti30xb, none of the above?
If I find an image of it on google, it might be easier to guide you through the steps.

Answer 9

ti30xlls

Answer 10

This is how I would punch it in, it might seem silly, but I love doing this instead of punching in a ton of brackets.

Under the 2nd button, log(2), Enter.
It will give you an ugly decimal.

Click STO>, Enter.
It has now stored that ugly decimal in your calculator.

Now click log(74), Enter.
Click Divide, Notice that it says\[\large Ans \div\]Ans refers to your previous answer that the calculator gave you.

So Ans in this case refers to the log(74)
Now press MEMVAR, choose A

So you should have something like ANS ÷ A,
That will get you your answer.

If that's way too confusing, we can do it another way, using brackets and such.

Answer 11

how do i choose a

Answer 12

(, log(74), ), ÷, (, log(2), ),

This would be the other way to do it. Maybe it's easier for you.
I put commas between each key you need to press.

Answer 13

answer 6.209

Answer 14

Yah looks right! :)

Answer 15

thank you so much have another problem if you have time but ill type in in so you get medals for both

Answer 16

New thread? k sounds good, just type @zepdrix somewhere in the description so i can come find it easier.

Answer 17

ok sounds good