Anyone do maths?
RealMan
Posts: 2,166
5/(a+bj) + 2/(1+3j) = 1
find a and b
where j = square root of -1.
I'm running out of ideas, and nothing seems to be working.
Its to do with steel downtube wall thickness, I swear.
find a and b
where j = square root of -1.
I'm running out of ideas, and nothing seems to be working.
Its to do with steel downtube wall thickness, I swear.
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So glad I finished school I can tell you that.0
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There is no mathematical answer. The square root of -1 is a NaN ie Not a Number therefore equation can not be solved. In simple terms there is no answer to "the square root of -1" or there is no number you can "square" (or multiply by itself) to give an answer of -1.0
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Don't worry about it docker0141, worked it out myself (with a little help from stw). a = 4 and b = -3.
The square root of -1 = i or j, depending on the context, by the way.
google square root of -1 if you don't believe me
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Complex numbers are fun
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Explain to me the square root of -j then.. that's the one thing I'm not quite clear on yet :shock:0
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I hate complex numbers, the bane of my first year at uni!0
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From google..square root(-i) = 0.707106781 - 0.707106781 i
(Square root 2)/2 - (Square root 2)/2 i = square root = i ?
Still don't understand.0 -
U cant square root a minus number ... arnt they called imaginery numbers or something...0
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I guess the way I would approach that is to work with:
(a + bi)^2 = -i
and solve for a and b. I haven't run through it on paper, but I would expect a couple of answers (maybe four).0 -
Yeah its probably simpler then I'm thinking it should be. Its too late now, I'll do it on monday (all maths is impossible during weekend, unfortunately..)0
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the square root of -1 is an imaginary number, the square root of -1 = i
don't ask me why it's all i remember from the head start i got on a level maths whilst in Year 100 -
My calculator won't square root -1 though like others have said it must be a mathmatical tool/imaginary number making sense has nothing to do with proper maths -_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_
Mongoose Teocali
Giant STP0
Why are MTB economics; spend twice as much as you intended, but only half as much as you wish you could afford? :roll:0 -
Stop it!
I come on here to read about wheels, and how to clean a Camelbak. This is reminding me of my SPC days!
Aaarrrghh!0 -
my head hurts :evil: i'm off out on my bike 2019 Ribble CGR SL
2015 Specialized Roubaix Sport sl4
2014 Specialized Allez Sport0 -
Don't bother the downtube is made of carbon.
See for your self. Click.0 -
seeing that i or j is the square root of an imaginary number, the square root of -j must therefore be equal to the square root of the non-negative version of j :?
make sense?
doncha love highschool? teaching me all this random stuff, we're doin' differentails at the moment...they're actually pretty interesting...but like most of the stuff on my course, very little of it has much real-world use.
Complex maths are awesome! simple maths is boring, useless and limited in its use
92% of teenagers have turned to rap. If your one of the 8% that still listens to real music put this in your sig
Walk (Ride) softly and carry a big fish
Yay, 100 hundred posts :-)0 -
Losing...will...to...live....0
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Fridge-Seal wrote:..we're doin' differentails at the moment...they're actually pretty interesting...but like most of the stuff on my course, very little of it has much real-world use.
...differentials are seriously useful stuff!0 -
That equation looks like J-notation. Fairly usefull for working out vectors etc, perticually resultant power etc for electrical engineers.0
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MountainPete wrote:...differentials are seriously useful stuff!
So's a calculator. Punch numbers in, press "equals", numbers come out. Simples!0 -
5 x 2.54 = 140mm. 0
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If A can dig a hole in 2 hours and
B takes 3 hours to dig the same sized hole and
C takes 4 hours to dig the same sized hole,
Question ? : Why don't they let A dig all the holes?...0 -
I give up, why?[b]Splottboy[/b] wrote:Why don't they let A dig all the holes?0 -
Because he is a A hole?0
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RealMan wrote:5/(a+bj) + 2/(1+3j) = 1
find a and b
Ignoring the a and b used above just for a moment:
a / (c + di) = ac / (c^2 + d^2) - adi / (c^2 + d^2)
2/(1+3i) = 0.2 - 0.6i
Back to using the a and b defined in your original example:
5 / (a + bi) = 0.8 +0.6i
so 5*b / (a^2 + b^2) = 0.6
and 5*a / (a^2 + b^2) = 0.8
Two equations in two unknowns, job done. Probably a bit confusing given the rubbish formatting and I've probably made a mistake somewhere, but you get the idea0 -
MountainPete wrote:...differentials are seriously useful stuff!
Yeah, I also do engineering studies a nd was thinking about how you could you them in mapping curves and such especially in technical drawings. (like plans for bikes )
What else can you do with them? there's probably tonnes of other stuff you can do, but my maths teacher won't tell me!92% of teenagers have turned to rap. If your one of the 8% that still listens to real music put this in your sig
Walk (Ride) softly and carry a big fish
Yay, 100 hundred posts :-)0 -
I studied Acoustic Engineering at university for 2 years and we use a lot of j (or i). It is useful when analysing wave forms (fourier analysis), as you have to express sine, cosine and tangent functions in terms of complex exponential equations in order to express a wave form as a function of time. :shock:
Crumbs, that bought back a lot of surpressed memories! That was like 10 years ago! :oops:
So, in terms of bikes, it is useful for suspension which is basically a mass, a spring and a damper - you can use differential equations to work out the damped natural frequency of a suspension fork, and therefore work out "critical damping" etc etc. How you express this in terms of "i" is beyond me now though!0 -
Splottboy wrote:If A can dig a hole in 2 hours and
B takes 3 hours to dig the same sized hole and
C takes 4 hours to dig the same sized hole,
Question ? : Why don't they let A dig all the holes?...
because if A dug all the holes, the three holes would take 6 hours to dig.
with A, B and C digging a hole each, the holes will all be dug in 4 hours, A will be totally smashed (he has been in the pub for 2 hours) and B will be well on his way too.
top result all round really.Whenever I see an adult on a bicycle, I believe in the future of the human race.
H.G. Wells.0 -
...........and one from the bottom please Carol................0
