Got Homework?
Connect with other students for help. It's a free community.
Here's the question you clicked on:
 0 viewing
jedai17
Group Title
can someone answer this quadric surface using completing the square ?thank you :)
x^2 + 4y^2  z^2  6x + 8y + 4z = 0
 one year ago
 one year ago
jedai17 Group Title
can someone answer this quadric surface using completing the square ?thank you :) x^2 + 4y^2  z^2  6x + 8y + 4z = 0
 one year ago
 one year ago

This Question is Closed

amistre64 Group TitleBest ResponseYou've already chosen the best response.1
get your like variables together and complete the squares .... which part is giving you pause?
 one year ago

amistre64 Group TitleBest ResponseYou've already chosen the best response.1
you can pull it apart into 3 quads if you like .... that might be less data to cull thru.
 one year ago

jedai17 Group TitleBest ResponseYou've already chosen the best response.0
i don't know how to solve this..i'm sorry
 one year ago

amistre64 Group TitleBest ResponseYou've already chosen the best response.1
do you know how to complete a square?
 one year ago

jedai17 Group TitleBest ResponseYou've already chosen the best response.0
it means that it will have a two factors in each variables..all in all it has a 6 factors?
 one year ago

jedai17 Group TitleBest ResponseYou've already chosen the best response.0
it is x^2  6x , 4y^2 + 8y and z^2 + 4z?
 one year ago

amistre64 Group TitleBest ResponseYou've already chosen the best response.1
lets go ahead and split this up into 3 different parts: x^2 + 4y^2  z^2  6x + 8y + 4z = 0 x^2 6x 4y^2 +8y z^2 + 4z now that its organized better, you just work each one in its own right .... complete the square for each part
 one year ago

amistre64 Group TitleBest ResponseYou've already chosen the best response.1
the key is, do you know how to complete a square? :)
 one year ago

jedai17 Group TitleBest ResponseYou've already chosen the best response.0
ah.. its z^2..
 one year ago

jedai17 Group TitleBest ResponseYou've already chosen the best response.0
i'm sorry i forgot how to complete a square..
 one year ago

amistre64 Group TitleBest ResponseYou've already chosen the best response.1
basically, you add and subtract a useful form of zero. square half the "x" term ..... for example: x^2 6x ; the x term is 6, 6/2 = 3, (3)^2 = 9. Lets add and subtract 9 x^2 6x + 9  9; and condense the square (x3)^2  9
 one year ago

amistre64 Group TitleBest ResponseYou've already chosen the best response.1
z will be trick only in that you have to account for the 
 one year ago

jedai17 Group TitleBest ResponseYou've already chosen the best response.0
x^2 6x ; the x term is 6, how it become 6/2?
 one year ago

amistre64 Group TitleBest ResponseYou've already chosen the best response.1
we are trying to make a complete square, a perfect square. numbers of the form (a+b)^2 are perfect squares: (2+5)^2 = 49, (3+1)^2 = 16, ... we want to condense this thing back into some (a + b)^2 form, thats all. In order to do that we have to modify its form, but not its value. Since adding zero changes nothing ... its useful to us. BUT what form of zero? lets expand (a+b)^2 = a^2 +2ab + b^2 ; let a=x (x+b)^2 = x^2 +2bx + b^2 notice that the b^2 is missing above. and we know that the "x" term in the middle is equal to 2b. 2b = 6 b = 6/2 = 3 b^2 = 9
 one year ago

amistre64 Group TitleBest ResponseYou've already chosen the best response.1
so, adding and subtract 9; 99 = 0 right? will allow us to "complete" the square and alter its form ... not its value
 one year ago

amistre64 Group TitleBest ResponseYou've already chosen the best response.1
4y^2 +8y 2b = 8 b = 8/2 = 4 b^2 = 16, +1616 = 0 4y^2 +8y + (1616) therefore 4y^2 +8y = (2y +4)^2  16
 one year ago

jedai17 Group TitleBest ResponseYou've already chosen the best response.0
oh..i see. thanks i will solve this..
 one year ago

jedai17 Group TitleBest ResponseYou've already chosen the best response.0
btw do you know about contour plotting?
 one year ago

amistre64 Group TitleBest ResponseYou've already chosen the best response.1
i would need a little more information to see if i have contour plotting rolling around in my head someplace :)
 one year ago

jedai17 Group TitleBest ResponseYou've already chosen the best response.0
do you know what kind of contour plot is this if f(x,y) = \[\sqrt{x^2 + y^2}\] ?
 one year ago

amistre64 Group TitleBest ResponseYou've already chosen the best response.1
so the height, or z, is dependent on x and y inputs if we hold one input constant, we can generate a cross section plot and such, are some ideas ive got z = sqrt(x^2+y^2) z^2 = x^2 + y^2 is a circle, and so im gonna extrapolate that this is a sphere or hemisphere as a guess
 one year ago

amistre64 Group TitleBest ResponseYou've already chosen the best response.1
http://web.monroecc.edu/manila/webfiles/calcnsf/javacode/calcplot3d.htm might be useful :)
 one year ago

amistre64 Group TitleBest ResponseYou've already chosen the best response.1
well it use to work fine, i guess they changed some stuff about
 one year ago

amistre64 Group TitleBest ResponseYou've already chosen the best response.1
http://www.wolframalpha.com/input/?i=sqrt%28x%5E2%2By%5E2%29 hmmm, its conic not spherical. it comes to a point at the origin and makes bigger circles as z gets bigger and bigger
 one year ago

jedai17 Group TitleBest ResponseYou've already chosen the best response.0
our topic to this is about contour plotting..
 one year ago

amistre64 Group TitleBest ResponseYou've already chosen the best response.1
dw:1361892976311:dw
 one year ago

amistre64 Group TitleBest ResponseYou've already chosen the best response.1
im not up to date on what contour plotting is, this is mostly from an old, decripid memory :)
 one year ago

amistre64 Group TitleBest ResponseYou've already chosen the best response.1
for your private message z = k z = x^2 + y for what values of x^2 + y does k = the stated set of values
 one year ago

amistre64 Group TitleBest ResponseYou've already chosen the best response.1
x^2 + y = 2 when y=x^2 2dw:1361893200001:dw
 one year ago

amistre64 Group TitleBest ResponseYou've already chosen the best response.1
in other words, the contour follows its reflection in the xy plane if that makes sense
 one year ago

amistre64 Group TitleBest ResponseYou've already chosen the best response.1
for any value of k, the reflected graph in the xy plane changes its y intercept so it will float up and down the y axis as needed
 one year ago

jedai17 Group TitleBest ResponseYou've already chosen the best response.0
what kind of contour plot is that?
 one year ago

amistre64 Group TitleBest ResponseYou've already chosen the best response.1
it looks like a repeition of a parabola to me, so its a type of cylindar right?
 one year ago

amistre64 Group TitleBest ResponseYou've already chosen the best response.1
dw:1361894575970:dw
 one year ago

jedai17 Group TitleBest ResponseYou've already chosen the best response.0
i don't know..but i heard that there is a graph named paraboloid, elliptical paraboloid etc..
 one year ago

jedai17 Group TitleBest ResponseYou've already chosen the best response.0
but i think it is elliptical paraboliod because you said that it is cylindar..
 one year ago
See more questions >>>
Your question is ready. Sign up for free to start getting answers.
spraguer
(Moderator)
5
→ View Detailed Profile
is replying to Can someone tell me what button the professor is hitting...
23
 Teamwork 19 Teammate
 Problem Solving 19 Hero
 Engagement 19 Mad Hatter
 You have blocked this person.
 ✔ You're a fan Checking fan status...
Thanks for being so helpful in mathematics. If you are getting quality help, make sure you spread the word about OpenStudy.