Recent comments in /f/explainlikeimfive

macedonianmoper t1_j6b9mpy wrote

Ah I see, then it's totally understandable, unlike fractions and negatives they don't really serve a purpose for day to day.

Education changes from place to place, I see a lot of people apparently had calculus in highschool while I only started it in college (this was only a few years ago), I did however learn about imaginary numbers in high school

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zachtheperson t1_j6b9875 wrote

Imaginary numbers become useful when working with a lot of advanced mathematics, and make equations work nicely.

A simple example though, is square rooting a negative number as you mentioned, but there's a little more to it. square_root(-1) = i, but that doesn't mean "no solution possible," it means that it's not possible at that moment. For example, if I plug that result into the function "f(x)=2+x^(2)" it now becomes a valid answer, because I am squaring the "impossible," answer of square_root(-1), cancelling out the square root

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Genshed t1_j6b7ngm wrote

I can't imagine an engineering degree I could have done.

Background: I went to high school in the late 1970s. We had geometry (Euclid style, not Descartes) and an algebra class for the students who were going to university.

Took an accelerated trigonometry class during summer bridge, and then failed Calculus I three times my freshman year.

That's when I shifted my academic goals from the natural sciences to history. I still retain my youthful enthusiasm for the sciences, which is why I learned about complex numbers in the first place.

Most of my friends view my ongoing efforts to understand mathematics as a charming eccentricity. As my eldest brother put it, paraphrasing Oscar Wilde, 'all logarithms are quite useless.'

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Antman013 t1_j6b7hbg wrote

Grey Goose is literally about marketing. The guy behind it spent thousands on slanted "surveys" where Grey Goose was compared against "well stock" brands, so naturally it would be the favourite. That led to the marketing campaign where the surveys were used as "proof" that it was the "best Vodka in the world". You can look up the history of it all. It;s a dang case study in marketing strategy.

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macedonianmoper t1_j6b7etg wrote

He understood, the thing is that the square root of a negative number is only impossible if you exclude "imaginary" numbers as a solution.

Very much like saying 3-6 is impossible if you don't think negative numbers are possible.

Just like banks might need negative numbers to say you're in debt, imaginary numbers are useful for other things, engineers use it to describe electricity in AC circuits for example

So you can say that imaginary numbers aren't possible, but that excludes real solutions that help you solve problems, very much like excluding fractional numbers would stop you from sharing an apple with a friend since you can either have an entire apple or none at all

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gwaydms t1_j6b63rb wrote

We didn't learn imaginary numbers until Algebra 1. Not a lot of us took that in Jr hi. Well, I did, but the excellent teacher we had went to teach at the high school, so we got the world's worst Algebra teacher. I'd ask her a question and be more confused afterward, so I learned to figure things out on my own. I felt bad for the kids who couldn't do that and got no help from our very nice but clueless teacher.

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TheNoidedAndroid t1_j6b4dly wrote

Two positive numbers can't multiply together to create a negative number, so it should be impossible.

But... if you 'imagine' that there IS some number that is multiplied by itself to get a negative number, you can actually use that 'imaginary' number to get useful results. All we do is define that number explicitly, so you say i*i= -1.

From this you get:

i^1 = i

i^2 = -1

i^3 = -i

i^4 = 1

A 'Complex number' is the sum of imaginary number and a real number. (for example 3i - 1) The complex plain is a coordinate system that plots complex numbers using the imaginary component for one axis and the real component for the other axis.

If you're using a regular x/y coordinate system, you can easily move the point on the X axis by adding or subtracting from the x value, and you can move the point on the Y axis by adding or subtracting from the y value, but what if you want to do something like rotating the coordinate around the origin? It's not super straight forward to find an operation that will turn 3x-y to -3y-x that will work for all coefficients. Sure, you could just add -4x -2y, but that only works for those specific coordinates.

But if you're using a complex plain, you unlock another operation! You can rotate the coordinate around (0,0) simply by multiplying it by some power of i!

Multiplying by 'i' rotates the coordinate 90 degrees clockwise, multiplying by i^x rotates the coordinate by 90*x degrees.

i^4 = i*i*i*i = (-1)(-1) = 1 because you've completed the 360 degree rotation returning the coordinate to where it started.

So if you're using 3i-1 instead of 3x-y, you can easily rotate it.

(3i-1) * i

3(i*i) - i

3(-1) -i

-3-i

And this operation will work regardless of what your starting coordinates are. Say you want to rotate -9i -5 by 270 degrees, you just multiply by i^3.

(-9i -5) * i^3

(-9i * i^3) + (-5 * i^3)

(-9i^4) + (-5i^3)

(-9 1) + (-5-i)

5i-9

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Shaman7102 t1_j6b4319 wrote

Had rotator cuff repair x2 on left shoulder. First surgery used the pin method and failed. Second surgeon used a thread anchor through bone technique much less painful and much happier with results. Takes a full year to heal to 100% but will never be as strong as original.

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