WAY off topic: Algebra equation

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curtisj76

curtisj76

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OK, my brain isn't working. I'm normally good with math but not today. How do you calculate an equation when the variable is an exponent? Anyone?

EX. 213.29 = 100(1.06)^x

Thanks
 
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adamscot89

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hey you have to use natural logs to get the exponent down to the bottom, so you would divide out the 100 first to get 2.1329=1.06^x. you take the natural log of 1.06^x and the natural log of 2.1329 and set them equal to each other: ln(2.1329)=ln(1.06^x). The x can then come down so you get ln(2.1329)=x*ln(1.06) so x = ln(2.1329)/ln(1.06) which if you do on a calculator = 12.99977261 or approx. 13.0 so
x=12.999... or about 13

thanks college algebra lol
 
Notorious B.E.N.

Notorious B.E.N.

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Lol we are doing that stuff in adv alg 2 right now. On your calculator push the y equals button on the top left. Enter your equation then push second graph and you can find what number you are looking for. Comes in handy when you have this sorta problem. Ex. I have
A car worth 8000. Each year its value increases 15 percent. When will the car be worth 12500? Equation--- 8000(1.15)^x
 
curtisj76

curtisj76

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Thanks! I'll give it a try.


PS The winner is adamscot89! I tried Big Papa's way and it wasn't working (or the operator wasn't doing it right). And tong just flat out failed!! :)
 
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thefuture37

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Notorious B.E.N. said:
Lol we are doing that stuff in adv alg 2 right now. On your calculator push the y equals button on the top left. Enter your equation then push second graph and you can find what number you are looking for. Comes in handy when you have this sorta problem. Ex. I have
A car worth 8000. Each year its value increases 15 percent. When will the car be worth 12500? Equation--- 8000(1.15)^x
Click to expand...

after college most people dont have TI-83's lol
 
K

kc8kir

New
Depends where you are and what resources you have:

Got an advanced calculator? Use the natural logarithm method.

Got a graphing calculator? Graph the equation and trace the value.

Got a calculator that can handle matrix operations? Make a matrix computation for the operation with a range of discrete values and pick the closest answer (interpolate).

Taking it on a test where no calculators are allowed (GMAT for example)? Hopefully it is multiple choice. Estimate or try plugging in the answer choices. Eliminate as many as possible.

Multiple ways around the golf course... er... math problem...
 
Bronco Billy

Bronco Billy

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Using Exponents is So Non Linear....

exponential.gif
 
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