Sec 3 Add. Maths overall help

• tr@nsp0rt_F3V3R

  1 Oct 08, 12:11

  hi all,

  I was doing some easy past year question, from my teacher, in prepation for the EOY, and i seems to be stucked at this question...

  1)      a) Find the value of k for which line y + kx = 12          (3)

  i am not sure if the question is wrong, but if you do have any solution, can u please help me with it.

  thankx ^^

   

• jay_rocks

  1 Oct 08, 12:13

  nothing wrong with the eqn.but forgotten how to do.

• ^tamago^

  1 Oct 08, 12:15

  what was the curve before this?
• tr@nsp0rt_F3V3R

  1 Oct 08, 12:18

  no curve... just that stand alone question... ...

  that's why i had been scretching my head over this

   

• eagle

  1 Oct 08, 12:21

  Are you very sure this is the full question?

  This is clearly an incomplete question

• SexyChin

  1 Oct 08, 12:23

  if nothing else is given, i believe k can represent all real numbers.

• tr@nsp0rt_F3V3R

  1 Oct 08, 12:34

  i think it is a -ve number...

  yea... i guess that's an incorect question then... thankx all btw...

  i'll confront the teacher tmr then ^^

• generation90

  1 Oct 08, 14:20

  Originally posted by tr@nsp0rt_F3V3R:

  i think it is a -ve number...

  yea... i guess that's an incorect question then... thankx all btw...

  i'll confront the teacher tmr then ^^

  yep it might be a negative number

  coz y + kx = 12

  then y = 12 - kx

  and k is obviously gradient right? haha

  i dont care alrdy

  i have finished both my amath and emath papers :)

• tr@nsp0rt_F3V3R

  1 Oct 08, 19:58

  gd 4 u...

  i had not even started any single paper... lol

  Friday 1st poaper, Engllish and E.  maths p. 1

  haiz~ we just cramp all withing 6 days... pervertic pricipal

• skythewood

  1 Oct 08, 20:15

  is there a picture of a graph, or is a coordinate given?

  you need to sub in the coordinates for y and x to solve for this one.

  or somehow get the gradient, and it will be equal to -k

• tr@nsp0rt_F3V3R

  1 Oct 08, 21:08

  Originally posted by skythewood:

  is there a picture of a graph, or is a coordinate given?

  you need to sub in the coordinates for y and x to solve for this one.

  or somehow get the gradient, and it will be equal to -k

  no graph given...  de qn should be wrong.. .too many unknowns in one eqn.

  by right it should acc. with another curve eqn.

  i'll just ask tmr lah... my friends friends all say it is high chance wrong even the Pro of de Pro said so... lolz

  nvm. thankx for de concern oso ^^

• marcos_84

  2 Oct 08, 02:11

  Not too sure if we need to have a real value or not. Maybe its like this? y + kx = 12 kx = 12 - y (Then divide throughout by x) k = (12-y)/ x Hope this helps!
• Xcert

  2 Oct 08, 10:25

  Originally posted by tr@nsp0rt_F3V3R:

  i think it is a -ve number...

  yea... i guess that's an incorect question then... thankx all btw...

  i'll confront the teacher tmr then ^^

  
  3 unknowns,1 equation...cannot solve...At least not by simultaneous equation method.

  Just clarify with the teacher can already...no need to confront....

• skythewood

  2 Oct 08, 10:34

  Originally posted by marcos_84:

  Not too sure if we need to have a real value or not. Maybe its like this?

  y + kx = 12
  kx = 12 – y (Then divide throughout by x)
  k = (12-y)/ x

  Hope this helps!

  and than you will need to sub in x and y to get the answer, so will need a coordinate

• tr@nsp0rt_F3V3R

  2 Oct 08, 17:17

  Hi all,

  so sry abt this. it is a wrong qn, as expected... ...

  the real qn should be:

  1)      a) Find the value of k for which line y + kx = 12 is tangent to curve to x2 + xy =12		(3)(3)
  	b) find the range of values of x for which 2x2 ≥ 5x + 12

  Quite a lot of impt. things that are lost... ... Haiz~! nub teacher... ...

  All well, at least i can do the qn, and reallt, thank you all for giving comments ^^

  pls dun scold me for de wrong qn haha...

• eagle

  2 Oct 08, 17:22

  One more question to add to ExamWorld :D

• tr@nsp0rt_F3V3R

  2 Oct 08, 17:26

  haha... ... thankx btw... having u to crack ur hed tgr...

  but i think this is rather a V. simple qn... lolz

  ... that is after knowing the second half... ... =.=

• generation90

  4 Oct 08, 10:22

  Originally posted by tr@nsp0rt_F3V3R:

  gd 4 u...

  i had not even started any single paper... lol

  Friday 1st poaper, Engllish and E.  maths p. 1

  haiz~ we just cramp all withing 6 days... pervertic pricipal

  hah really? my exams finished on monday (2 more daysss) :D ahh, i need a breakk.. sighs..

• generation90

  4 Oct 08, 10:23

  finish*. lols

• dadeadman1337

  4 Oct 08, 12:02

  Qn  1a) is k=4?

  1b) is x ≥ 4  or  x smaller than or equal to -1.5? {cant type the symbol < with a line underneath}
  

• tr@nsp0rt_F3V3R

  4 Oct 08, 12:37

  a)       x2 +x(12-kx)=12 x2 + 12 x – kx2 = 12 (1-k)x2 − 12x − 12 =0   b2−4ac = 0 144 − 4(1−k)(−12) = 0 144 − 48 ( 1−k ) = 0 144 – 48 + 48k = 0 48 k = -96 k = -2

  b) 2x2 ≥ 5x + 12 2x2−5x − 12 ≥0 (2x + 3)(x − 4) ≥0 x≥ - 3/2           or     x≥ 4

• tr@nsp0rt_F3V3R

  4 Oct 08, 12:42

  App. that would be the answer i have gotten... ...

  gow did u get for 1a?

  or is there any mistake in my steps?

   

  ==> my teacher just say go home and try, should be a easy qn, just give us the second half then go on to de other qn...

  so xian