2008 Second Semester MATHS课程问答帖(请用英文提问)

花花花狸鼠

consider the system of linear equatoins,
x+y+kz = 2
3x+4y+2z = k
2x+3y-z = 1
Give the solution when k=3, describing the relationship of the planes in this instance

i tried to transform the above to reduced row echelon form which gives the solutions
(1 1 3 2; 0 1 -7 -3; 0 0 0 0), this means the system has infinitely many solutions, am i right?
from here, i don't know how to do further, what are the solutions represent? if there are infinitely many solutions, the three planes meet on a line or a plane by the three forms which are 3 coincident planes, intersecting is a plane, 2 coincident planes, intersection is a line, intersection is a line. how can i identify which one is which from the above solutions? thx!

jennyyang

Maths 108, ASSIGN 2, Question 8
Could you please explain to me how should I do this question? Its confusing

jennyyang

q8 Assign 2

suppose P and Q are two distinct planes in R^3. what sort of set could their intersection be? answer in words and give a sketch to show the possibilities.

ycho126

Q3
Find the values of k for which the matrix A = [1 -1 -2 ; 3 k k ; 3 1 k] is invertible.

can i have some hints of how to do this question please?? thx so much

萨米

原帖由 ycho126 于 2008-5-15 18:05 发表
Q3
Find the values of k for which the matrix A = [1 -1 -2 ; 3 k k ; 3 1 k] is invertible.

can i have some hints of how to do this question please?? thx so much

Only the determinent is not 0.

ycho126

so do u mean i just randomly choose a real number to let det(A) not equal to 0?
for example, det(A) = 2

萨米

原帖由 ycho126 于 2008-5-16 15:51 发表
so do u mean i just randomly choose a real number to let det(A) not equal to 0?
for example, det(A) = 2

Make it to REF and determine the det.

ycho126

thx so much!!

however, i got another problem which is.....
Use the formal definition of differentiation as a limit to find the derivative f'(x).  where f(x) = 1/(x-1).
I know the ans is -1/(x-1)^2, but i can't get the answer by using "formal definition"......

tokidoki_y

question 9
f(x) = (x^2-1)/(2x^2-2x-12)
how do we find the asymptotes of the graph of f and any discontinutities??
and also what should we do to find t he relative extrema??

thanx.

ty_srb$

how do you do math208 assg 4 q1.

also. i need a tutor for 208. any advice or any1 that can help me ma?
thx la..

papa_ohyeah

help
how to integrate x/((1+2x)square root).dx
dont know how to type !
hope u understand

ccjj

looking for a maths108 tutor... urgently please...

please email me...

cathyfee

303B25 just wondering can u help with math 253 thx!!

CEOjennifer

here's a stupid question, does anyone know what is the criteria for Math102 to get A+? Is it 90 or 95 or 85???

摇得你好滚

anyone help in second semester math208 assignment?

摇得你好滚

3. (8 marks) Let U consist of all vectors in 3-dimensional Euclidean vector space R3 each of whose entries is the same, that is U = {(a; b; c) : a = b = c∈R}

(b) What is the dimension of U?
(c) Describe U geometrically.
(d) State a system of linear equations that defines U.