Primitive Function (1 Viewer)

[Aysce]

You guys will probably think I'm retarded, but what how do you do Q:

Given d^2y / dx^2 = 8 and dy/dx =0, and y =3 when x=1, find the equation of y in terms of x.

Thanks.. :$

 

[deterministic]

You guys will probably think I'm retarded, but what how do you do Q:

Given d^2y / dx^2 = 8 and dy/dx =0, and y =3 when x=1, find the equation of y in terms of x.

Thanks.. :$

Remember integration reverses the differentiation process
integrate d^2y/dx^2 to get dy/dx=8x+C (don't forget constant of integration)
Then sub x=1 and dy/dx=0 into above to get 0=8+C -> C=-8
Then apply the same process again to find that y=4x^2-8x+7

 

[bleakarcher]

d^2y/dx^2=8
Integrating w.r.t.x:
=>dy/dx=8x+C
When x=1, dy/dx=0,
=>8(1)+C=0
:.C=-8
Hence, dy/dx=8x-8
Integrating again w.r.t.x:
=>y=4x^2-8x+C
When x=1, y=3,
=>4(1)^2-8(1)+C=3
:.C=7
Hence, y=4x^2-8x+7

 

[SpiralFlex]

Now we know, at














Passing through






The equation is,

 

[Peeik]

See the attachment. The method is correct, but i didnt check if id made any silly mistakes haha. Ask me if you didnt understand it.

 

[SpiralFlex]

Use Latex,

http://www.codecogs.com/latex/eqneditor.php

Makes the job easier!

 

[Aysce]

But can't you only sub in x=1 if y=3?

 

[Peeik]

Use Latex,

http://www.codecogs.com/latex/eqneditor.php

Makes the job easier!

hey spiralflex how do you use latex when replying? I cant seem to find the fx button that they used to have :S?

 

[nightweaver066]

hey spiralflex how do you use latex when replying? I cant seem to find the fx button that they used to have :S?

Have to type in

 

[Peeik]

But can't you only sub in x=1 if y=3?

The question you typed said "...dy/dx =0, and y =3 when x=1, find the equation of y in terms of x." This means that dy/dx =0 and y = 3 occurs WHEN x = 1. You just need to get use to the wording of the question i guess

 

[SpiralFlex]

This question is from the MIF book Ch 2 question 10 if I recall correctly. I was helping people with it the other day.

You guys will probably think I'm retarded, but what how do you do Q:

Given d^2y / dx^2 = 8 AND dy/dx =0, AND y =3 WHEN x=1, find the equation of y in terms of x.

Thanks.. :$

Here are the trigger words.

 

[Aysce]

@ Pee : Ohh I sorta get it now

Thanks guys

@ Spi : I feel less simpleminded now zzz

 

[SpiralFlex]

Hence why I enjoy feasting on delicious humans.

 

[bleakarcher]

when i use the codecogs link i cant make spaces or paragraph, how do i?

 

[SpiralFlex]

Spaces do not appear when you type it in the equation editor. To avoid this, you must click the space symbol (Middle somewhere, it's two adjacent boxes) in the equation editor.