help with using a ti-84 to solve exponential equation

D

daemon

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Dec 17, 2005
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Hello!

I am supposed to use a calculator to obtain a decimal approximation to 2 decimal places for the following equation.

4^x+7 = 2


This is the first time I have used one of these calculators and I am having quite a time trying to figure it out.
 
Do the solving symbolically, until you can get "x = (something with numbers)". Then enter the numerical expression (the "something" bit) into the calculator. The buttons are fairly straightforward; just typeset your expression (using parentheses, as necessary), and then press "ENTER".

Eliz.
 
I believe the 84 has SOLVE capability. I have a TI-92 and it's virtually the same except for the keyboard. Do you have the function keys(F1, F2, F3,.... etc.)?. Do you have the manual that came with it?. If you do, that would be the thing to do. These calculators are wonderful and, actually, very user-friendly.

Is there an F2 key?. If there is, see if the solve function isn't under it.

Is that \(\displaystyle 4^{x}+7=2\) or \(\displaystyle 4^{x+7}=2\)?
 
If it were \(\displaystyle 4^x + 7 = 2\) then there would be NO REAL SOLUTION! WHY?
 
sorry, I should have written that as

4^(x+7)=2

The calculator does have the function keys. It seems to be a very useful calculator, just takes some time getting used to where everything is I guess.
I'm digging around for my instruction manual right now.
 
pka was right, I should've seen that \(\displaystyle 4^{x}+7=2\) isn't an option. Head-in-the-butt syndrome.

Anyway, push the F2 key and see if there is a SOLVE option under it. If there is, write back and I will step you through it.
 
why a calculator?
x is obviously = -6.5 : 4^(1/2) = 2
 
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