Physics question... halp??

[tigon]

2V1 + 3V2 = -5

2V1² + 3V2² = 35

solve for V1 and V2...

I can do it in ms paint if you can't read the equation...

thanks

 

[morocco_mole]

(-5 - 3v2)/2=

 

[MCIRONCOCK]

I can't believe i passed physics on my first try

 

[morocco_mole]

the square root of ((35 - 3v2squared)/2)

solve for v2

 

[Aaaron.]

you are now NS's resident nerd

 

[Aaaron.]

oh

and i maxed out your karma =)

 

[shabinka]

Let me try this out real quick.

 

[tigon]

did anyone get an answer because I did it that way and I still couldn't ge t the right answer

 

[shabinka]

Basically, I solved for V1 in terms of V2. Which V1= (-5-3V2)/2
Plug that into the second equation.
{2[(-5-35V2)^2/2]} + 3V2^2=35
Set the equation equal to zero, so your final equation is, 7.5V2^2+15V2-22.5=0
I guess you do the quadratic formula from there (-b+radical(b^2-4AC)/2a) but for some reason, that's not working but looking at the graph the 0's are x=1 and x=-3. I'm assuming you want 1. So plug 1 into the other equation, V1=-1.

 

[tigon]

hm... my key says

V1=2 V2=-3 OR V1=-4 V2=1

not sure if its a typo or what

 

[shabinka]

OH! You are subtracting a negative when you are solving for V1 so, 2V1=-8, V1=-4. I can explain it better if you want to send me a message on AIM.

 

[shabinka]

Basically, I solved for V1 in terms of V2. Which V1= (-5-3V2)/2
Plug that into the second equation.
{2[(-5-35V2)^2/2]} + 3V2^2=35
Set the equation equal to zero, so your final equation is, 7.5V2^2+15V2-22.5=0
(I can't believe I didn't notice this earlier)
Take out a 7.5. 7.5(V2^2+2V2-3)=0.
So, the V2^2+2V2-3 factors to (V2+3)(V2-1). Solve for V2, which gives you -3 and 1. Ok, so that was simple.
Then just plug one of those numbers into the first eqation for V2 (2V1+3V2=-5) to solve for V1.
The V2^2 is V2 squared incase you haven't noticed, and the weird brackets are just how I grouped things so I could understand them.

 

[tigon]

alright I got it... thanks mate

 

[shabinka]

Yeah man, just drop me a message if you need any more physics help.

 

[morocco_mole]

that sounds right, one equation is a strait line and the other is a curved line so they can intersect twice

like this

\ /

\ /

----x-------------------------------x---------

\ /

\ /

_____

i think

 

[tBatt]

i noticed there was a lack of an icon in this thread, so i decided to ruin the trend

too bad this has nothing to do with physics.

 

[morocco_mole]

thats interesting

 

[B-VUR]

I noticed that as well