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June 26, 2022, 11:53:22 am

### AuthorTopic: algebra help  (Read 1284 times) Tweet Share

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#### annaoh_2003

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##### algebra help
« on: January 16, 2022, 10:06:09 pm »
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Hi, im wondering if someone can explain to me how to solve this equation??
« Last Edit: January 16, 2022, 10:08:32 pm by annaoh_2003 »

#### mabajas76

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##### Re: algebra help
« Reply #1 on: January 16, 2022, 10:30:36 pm »
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So here is the trick, you can assign 2^x a value, lets say t. So 2^2x=t^2, -15x2^x=-15t etc
So you get t^2-15t-16=0, the soloutions for this are t= 16 or -1, using t=16 you get 16=2^x, then 16=2^4 and so x=4.
"Don't give up, and don't put too much effort into things that don't matter"-Albert Einstein, probably.

#### Pariz

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##### Re: algebra help
« Reply #2 on: February 19, 2022, 10:35:34 am »
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Hey - for these types of questions you pretty much wanna reduce it to a simpler quadratic equation.

you would let a = 2^x, then substitute into given equation.

so you get

a^2-15a-16=0
(a-16)(a+1)=0
a=16 or a=-1
You ALWAYS reject negatives. resub back to solve for x

2^x=16=2^4
and so x=4

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hope it helped
« Last Edit: February 19, 2022, 06:21:01 pm by insanipi »