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November 26, 2014

November 26, 2014

Posted by **Amy** on Thursday, January 27, 2011 at 5:20pm.

2^(2x) + 2^(x) -12 = 0

Steps too

I tried solving this but I ended with ln(12) / 2ln(2) + ln(2) but the real answer is supposed to be ln(3) / ln(2) or 1.585

- Precalc -
**Reiny**, Thursday, January 27, 2011 at 5:39pmlet 2^x= y

then your equation becomes

y^2 + y - 12 = 0

(y+4)(y-3) = 0

so y = -4 or y = 3

then

2^x= -4, which is not possible

or

2^x = 3

ln both sides

ln(2x) = ln3

x ln2 = ln 3

x = ln3/ln2 = appr. 1.58

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