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/sci/ - Science & Math


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9685245 No.9685245 [Reply] [Original]

Why direct proportionality is defined as y=kx where k is a constant instead of y=k+x?

>> No.9685256

you're an idiot

>> No.9685261

>>9685256
why you are so rude?

>> No.9685263

>>9685261
sissy brainlets need to be bullied

>> No.9685264

>>9685263
how can i turn myself into a chad non-brainlet?

>> No.9685266

>>9685245
because the word "proportional" literally implies multiplication, dumbass

>> No.9685267

>>9685264
By wearing girl socks

>> No.9685271

>>9685266
it doesn't.

>> No.9685272

>>9685245
as in a proportion of
or a portion/fraction of

>> No.9685275

>>9685272
you are just saying y=kx.

>> No.9685284

>>9685275
yes, k=y/x its a fixed fraction. a constant.

or a portion

proportional

>> No.9685288

>>9685284
you can say the same to k=y-x, if x rises, x must rise.

>> No.9685290
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9685290

>>9685288
y*

>> No.9685294

>>9685288
getaloadofthisguy.png

>> No.9685299

>>9685294
typo, sorry boi

>> No.9685322

>>9685288
I tried to help you.

But you need to understand fractions before you can have any hope of understanding proportionality (linear functions).

>> No.9685326

By the way, I learned this stuff in junior high, when I was 14 years old.

>> No.9685330

>>9685326
You learned about multiplication at 14?

>> No.9685333
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9685333

>>9685330
>>9685326
lmoa

>> No.9685349

>>9685330
I think I learned multiplication in grade 3.
Fractions in grade 5.
Linear functions in grade 7.
Algebra by grade 9.

I dont remember desu.

>> No.9685356

>>9685245
because when you double one, you double the other so you keep the proportions the same.

>> No.9685366
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9685366

>>9685349
Damn you are soooo smart, but can't even explain why proportionality y=kx.
You just needed to say that K is the slope, so it changes the relation of X with Y.
While y=k+x has a slope 1, it implies that the relation of X with Y is always 1, K is B in the slope intercept formula.

>> No.9685376

>>9685366
whatever

I thought perhaps if OP knew where the word came from it might help him/her understand...

Explain things to little kids however you want, and I'll do the same.

>> No.9685396

>>9685245
y=kx means that the function will always be the same line when graphed
If y=k+x the line graphed will always be offset from origin by whatever value k is which doesn't do as well of a job at explaining the concept as y=kx does since y=kx never moves anywhere.

>> No.9685421

>>9685288
wha?
it's like you didn't even read his post

>> No.9685456
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9685456

>>9685245
>The AGP's autism isn't strong enough and he is a brainletlite

Cute

>> No.9685461

Not OP here but I kinda understand what OP is trying to ask but I understand that proportion means y=kx

however lets say that the baseline is y=x
then we apply the proportion y=kx
Now, couldn't you take kx=q=(x+r) (where r=kx-x)

>> No.9687339

>>9685245
Apparently people can't explain this. It's not complex at all- I was taught it at age 12- but anyway...
Direct proportionality is when if you multiply the x value by a certain factor and only allow the y value to change (rather than another constant) the y value gets multiplied by the same factor.
So, let's look at your equations.
Y = k + x is not a direct proportionality, as k + 2x ≠ 2 y (using factor 2, but any works).
Y = kx however is a direct proportionality, as k * 2x = 2kx = 2y.
Y = k + x describes a straight line with gradient 1 that passes through variable y-intercept k.
Y = kx describes a straight line through the origin (i.e. y-intercept = 0) with variable gradient k.

>> No.9687345

>>9687339
Everyone has explained it like that you underage, self absored retard.

>> No.9687411

>>9685330
im laughing so hard holy shit.