Mathematics: Post your doubts here!

[Saahil Parikh]

Hello everybody.
I'm having a bit of a problem in mechanics, Resolving Forces to be precise. If someone can post notes on Resolving Forces it'll be really helpful. Thanks

 

[Near]

Help needed for Nov 06 Question 08

 

[Khadija_1234]

Values of a, b and c for which the equation ax+by+c=0 doesn't represent a straight line?

 

[syed1995]

the cubic root of 2 + the cubic root of 16
Thats my doubt. Plz help. thks

I am not writing 3 in front of √ but here √ means 3√ (Cube Root of)
√2 + √16
√2 + √(2*2*2*2) 16 can also be represented as 2^4..
√2 +√[(2^3)*2]
now taking the cube root of 2^3 will give you 2.. so 2 will come out of the root sign.
√2 + 2√2
3 √2

so final answer will be 3* (Cube root of 2)

Hope that helps.. also resolve the big numbers into the power of their standard form (TAKING LCM to find the power of standard form is very helpful in this) and it shouldn't seem too hard with practice.

If you have any more questions.. just don't hesitate to tag me..

Cheers

 

[JoNaTHaN Wijaya]

Help me pls....
9231_S12_QP_12
number 3,5 AND 6 pls thx so much

 

[JoNaTHaN Wijaya]

Help me pls....
9231_S12_QP_12
number 3,5 AND 6 pls thx so much

 

[M.Kabir Nawaz]

what is the formulae for finding the sum of geometric sequence...?

 

[RadzMau]

Can you pls help out with that question?

 

[Killer_555]

can you help me with these questions :
1) Find all values of k if the equation x^2 + (k-2)x + 10-k = 0 has equal roots.
2)The equation x^2 - 2x + 1 = p(x-3) has equal roots. Find the possible values of p.

 

[Jaspreet Dhaliwal]

Can someone help with october november 2011 question paper 12 question 6, 7, 8 all parts thanks!

 

[kaushar]

i really need help for may/june 2013 no 6 paper 12

 

[Ahmedm96]

in j12 p4 v1 no7 why didn't we consider rings wheight. in (I)

 

[gonde96]

any maths problems that are unsolved you may ask me

 

[Dudu]

Can you pls help out with that question?

OD is (4i+4J+5k)

Firstly to get to O to D you need to go 5 steps UPWARDS (and it says top is 5m above base) So K = 5

Then DE = 6 and OA =14 so the difference is 8 there. so the two bits at the side are 4 each. (4 + 8 + 4 = 16)
So we need to move in the "i" direction 4 steps. i = 4

Finally note that D is not directly under O so you have to move half the length of OC to get under it. 8/2 =4. So 4J

(4,4,5)

Mag is square root of (4^2 + 4^2 + 5^2) = Square root of 57

Try OB now.

 

[Dudu]

can you help me with these questions :
1) Find all values of k if the equation x^2 + (k-2)x + 10-k = 0 has equal roots.
2)The equation x^2 - 2x + 1 = p(x-3) has equal roots. Find the possible values of p.

Just use the discriminant. b^2-4ac = " "

"=0" if one root or equal roots
"<0" if no roots
">0" for two roots

 

[kaushar]

any maths problems that are unsolved you may ask me

i did ask a question do you mind reply me plzz...

 

[$~SauD~$]

i really need help for may/june 2013 no 6 paper 12

 

[$~SauD~$]

Now someone help me.
http://olevel.sourceforge.net/papers/9709/9709_s13_qp_32.pdf
Question 5.
I did all and came to a part where >>> 3x^2 - 6ax - y^2 = 0 <<<
Now mark scheme says to eliminate 'y'. So how to eliminate it?

 

[Kumkum]

Now someone help me.
http://olevel.sourceforge.net/papers/9709/9709_s13_qp_32.pdf
Question 5.
I did all and came to a part where >>> 3x^2 - 6ax - y^2 = 0 <<<
Now mark scheme says to eliminate 'y'. So how to eliminate it?

ok from "3x^2 - 6ax - y^2 = 0", you can make y^2 the subject of the formula
so, "y^2 = 3x^2 - 6ax"
then substitute "y^2" into the equation of the curve and solve for "x"

 

[Dudu]

i really need help for may/june 2013 no 6 paper 12

Ok. So we have
OA (1i, -2j, 2k) and OB (3i, pJ, qK)

for i) It says both are parallel. The clue is the "i" in both vectors. It goes from 1 to 3. Therefore "x3" OA to get to OB.

So
-2 x "3" = -6 = p
2 x "3" = 6 = q

for ii) it says 90 degrees which means the dot product =0
(1,-2, 2) and (3, p, 2p)
so:
(1 x 3) + (-2 x p) + (2 x 2p) = o
3 - 2p + 4p = 0
2p = -3
p=-3/2

finally iii)

AB means b-a (for e.g CB means b-c, AD means d-a etc etc)
so: (3, 1, 8) - (1, -2, 2) = (2, 3, 6)

To get the Unit vector first find the Magnitude of it which is Square root of (2^2 + 3^2 + 6^2)
Which is square root of 49 ==> 7

Lastly you gotta divide vector by this number.
Hope you understood!