MegaSack DRAW - This year's winner is user - rgwb
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Ok, finally got to grips with the advanced algebra part of my coursework.
Or so i thought. Now i reckon this is easy and my brain has reached saturation point but im really struggling with this one.
Oh and realman if u read this. Cheers for the quadratic equation advice. Made everything so simple 🙂
Anyhoo i have hopefully attached a pic of the offending question. Please help 🙂
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Is that the whole equation? I don't really see what is there to solve and unless I've forgotten how to use my calculator (Which is very possible), the rhs is not 16...
Unless e is an unknown and not what I think of as e...
I think 'e' is a variable in this case like 'x' would be, rather than the normally associated constant.
(Otherwise, the correct answer would be 'false').
Yep thats the whole equation, e relates to growth and is 2.7182.
Now my assumption was to transform and solve it for t.
a quick in the head says
t = -2 * ln(1/3)
e^(-t/2)=1/3
I can't remember how to take it further...
Oh I though the t was a 1... That makes more sense.
Quick in the head is the same as klunk but with a minus sign in front. I was always prone to getting minus signs wrong though
Edit. Didn't see the minus on klunks answer. That's what I get as well.
Yea it has pickled my head for now. Just gotta sleep on it and see if that does me any good. i spent 3 bloody days figuring out linear equations with 3 variables so this should be a doddle 🙂
klunk has it I think.
Just remembering old math:
16=24(1-e^(-t/2))
16 = 24 - 24e^(-t/2)
-8 = -24 e^(-t/2)
multiply by -1 both sides:
8 = 24 e^(-t/2)
1/3 = e^(-t/2)
take logs:
ln(1/3) = (-t/2)*ln(e)
-2ln(1/3)/ln(e)=t
But ln(e) = 1
-2 ln(1/3) = t
Which makes t=+2.19722457733624 (since ln(x) where x<1 is negative).
Hi Emsz, if you're about!