Math Question

[czech09]

Calc2 sucks but anyways this is a much simpler question than that...how the hell does x^2 plus y^2 = 3y equal x^2 + (y-3/2)^2= (3/2)^2 ?

 

[wfbberzerker]

im not doing your homework.

 

[dighn]

expand the latter

i think you can get the latter by completing the square

 

[Mday]

Originally posted by: czech09
Calc2 sucks but anyways this is a much simpler question than that...how the hell does x^2 plus y^2 = 3y equal x^2 + (y-3/2)^2= (3/2)^2 ?

mind typing that correctly...

 

[RedCOMET]

Originally posted by: dighn
expand the latter

i think you can get the latter by completing the square

That could make sense, but then why is there a (y-3/2) term?
Shouldn't it just be (3/2)y ??

Edit: As a side note, i suck at math,but some how managed to pass calc 1, 2 and 4. didn't have to take 3.

 

[archcommus]

Originally posted by: czech09
Calc2 sucks but anyways this is a much simpler question than that...how the hell does x^2 plus y^2 = 3y equal x^2 + (y-3/2)^2= (3/2)^2 ?

How does one equation "equal" another?

 

[chuckywang]

Originally posted by: czech09
Calc2 sucks but anyways this is a much simpler question than that...how the hell does x^2 plus y^2 = 3y equal x^2 + (y-3/2)^2= (3/2)^2 ?

x^2+y^2=3y => x^2+y^2-3y=0

add (3/2)^2 on both sides

x^2+y^2-3y+(3/2)^2=(3/2)^2

Factor LHS with all terms that has a "y" in it.

x^2+(y-3/2)^2=(3/2)^2

Now you know the location of the center of your circle and the radius of that circle.

 

[everman]

42

 

[Koenigsegg]

Originally posted by: chuckywang

Originally posted by: czech09
Calc2 sucks but anyways this is a much simpler question than that...how the hell does x^2 plus y^2 = 3y equal x^2 + (y-3/2)^2= (3/2)^2 ?

x^2+y^2=3y => x^2+y^2-3y=0

add (3/2)^2 on both sides

x^2+y^2-3y+(3/2)^2=(3/2)^2

Factor LHS with all terms that has a "y" in it.

x^2+(y-3/2)^2=(3/2)^2

Now you know the location of the center of your circle and the radius of that circle.

I have no idea what that means but I'm just going to quote it and say you're right and appear smrt.

 

[eLiu]

Originally posted by: archcommus

Originally posted by: czech09
Calc2 sucks but anyways this is a much simpler question than that...how the hell does x^2 plus y^2 = 3y equal x^2 + (y-3/2)^2= (3/2)^2 ?

How does one equation "equal" another?

If you expand the second equation, you can get the 1st equation...look:

2nd equation: x^2 + (y-3/2)^2 = (3/2)^2
x^2 + y^2 - 2*(3/2)*y + (3/2)^2 = (3/2)^2
x^2 + y^2 = 3y

OP...see that? Reverse the process to do what you originally requested. This thing is called 'complete the square' or something like that. It's just the expansion (a+b)^2 used in a kinda indirect setting.

 

[JParker001]

oops

 

[NeViKoo7]

Originally posted by: Koenigsegg

Originally posted by: chuckywang

Originally posted by: czech09
Calc2 sucks but anyways this is a much simpler question than that...how the hell does x^2 plus y^2 = 3y equal x^2 + (y-3/2)^2= (3/2)^2 ?

x^2+y^2=3y => x^2+y^2-3y=0

add (3/2)^2 on both sides

x^2+y^2-3y+(3/2)^2=(3/2)^2

Factor LHS with all terms that has a "y" in it.

x^2+(y-3/2)^2=(3/2)^2

Now you know the location of the center of your circle and the radius of that circle.

I have no idea what that means but I'm just going to quote it and say you're right and appear smrt.

heh, even with highschool calc I knew that. I <3 math.

 

[czech09]

Originally posted by: NeViKoo7

Originally posted by: Koenigsegg

Originally posted by: chuckywang

Originally posted by: czech09
Calc2 sucks but anyways this is a much simpler question than that...how the hell does x^2 plus y^2 = 3y equal x^2 + (y-3/2)^2= (3/2)^2 ?

x^2+y^2=3y => x^2+y^2-3y=0

add (3/2)^2 on both sides

x^2+y^2-3y+(3/2)^2=(3/2)^2

Factor LHS with all terms that has a "y" in it.

x^2+(y-3/2)^2=(3/2)^2

Now you know the location of the center of your circle and the radius of that circle.

I have no idea what that means but I'm just going to quote it and say you're right and appear smrt.

heh, even with highschool calc I knew that. I <3 math.

There is no need for calc for that, it's algebra thanks for the help.

 

[RedCOMET]

Originally posted by: chuckywang

Originally posted by: czech09
Calc2 sucks but anyways this is a much simpler question than that...how the hell does x^2 plus y^2 = 3y equal x^2 + (y-3/2)^2= (3/2)^2 ?

x^2+y^2=3y => x^2+y^2-3y=0

add (3/2)^2 on both sides

x^2+y^2-3y+(3/2)^2=(3/2)^2

Factor LHS with all terms that has a "y" in it.

x^2+(y-3/2)^2=(3/2)^2

Now you know the location of the center of your circle and the radius of that circle.

Nice job. When it comes to stuff like this, i can't cut it any more