Any1 here know maths?

[UCE]

dosen't seem that hard to undertand, give me a minute.

 

[UCE]

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^^^^^^ click on this, the Answer is there pretty simple actually.

 

[Jessika Uzumaki]

Omgosh dude... I feel sorry for you, I can't stand math.... I only liked math when I was a freshman in high school that's only b/c I had an awesome teacher named Mrs. Flores...but sadly she left to teach middle school. Then for sophomore yr. I had that b*tch Mrs. Groves she ain't teach me sh*t, but I still passed Geometry with a B and it's all thanks to Youtube!!!!! <3

 

[Uzumaki Naruta]

Probably stupid to ask here, but anyway..

y'= 1+y/x
substitute: u= y/x => y= u.x

now I get:
y'= u'.x+u

but why? how did I get that :/

You got that because you were derivating what you were going to substitute without substituting.

y= ux
y´= u´x + u.x´ (Since x´=1)
y´ = u´x + u

You never put your substitution in the main equation in the first place.

 

[trick master]

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Yeah, but how did i get that?

you do realize that whatever you do on one side of the equation, you must do it on the another one, right?
for instance

x=2; y=2

x=y

x+1=y+1

50*x=50*y

and so on

so u=y/x can be written as x*u=y/x*x

which is equals to x*u=y