Mathematics: Post your doubts here!

[asexamskillme111]

Hey.
http://www.xtremepapers.com/papers/CIE/Cambridge%20International%20A%20and%20AS%20Level/Mathematics%20(9709)/9709_s04_qp_3.pdf
question 9 part 2 please.

 

[whitecorp]

whitecorp doubt in differential equations

View attachment 16370

There you go, the full solutions. Hope it helps. Peace.

 

[whitecorp]

Hey.
http://www.xtremepapers.com/papers/CIE/Cambridge International A and AS Level/Mathematics (9709)/9709_s04_qp_3.pdf

question 9 part 2 please.

You may wish to refer to this which I previously solved for someone else:

Solutions for Q9(ii)

Hope it helps. Peace.

 

[Tabi Sheikh]

well i think no

Thanks Buddy

 

[shanky631]

For this question I get two critical values x=1 or x=5/3. But in the mark scheme they only consider x=1. Why??? Plz whitecorp or anyone help me.

 

[parthrocks]

View attachment 16393
For this question I get two critical values x=1 or x=5/3. But in the mark scheme they only consider x=1. Why??? Plz whitecorp or anyone help me.

See bro substitute value of 5/3 and then u get 0.33333333 left hand side and -0.333333 on the right hand side which means that 0.33333 is not less than - 0.333333 and so it's false....and we done take it though confirm with whitecorp

 

[shanky631]

See bro substitute value of 5/3 and then u get 0.33333333 left hand side and -0.333333 on the right hand side which means that 0.33333 is not less than - 0.333333 and so it's false....and we done take it though confirm with whitecorp

thnx ya it makes sense.

 

[parthrocks]

thnx ya it makes sense.

Ya bro so tried any vectors sums..

 

[GorgeousEyes]

A ball is thrown vertically upward and is caught at the same height 3 seconds later. Find (a) the distance it rose (b) the speed with which it was thrown .

 

[GorgeousEyes]

A ball is thrown vertically, with a speed of 7 m/s from a balcony 14 m above the ground. Find how long it takes to reach the ground if it is thrown (a) downwards (b) ... Find also the speed with which it reaches the ground in each of these cases.

 

[asexamskillme111]

http://www.xtremepapers.com/papers/CIE/Cambridge%20International%20A%20and%20AS%20Level/Mathematics%20(9709)/9709_s03_qp_3.pdf

question 3. solving the quadratic equation that i get from squaring both sides, i get 2 values for x. the marking scheme says x<1 is the only answer.

 

[bloody_mary]

can someone please help me with some unit vector questions? I totally forgot how to do them again.


The vector A has x and y and z-components of 8, 12, and -4 units . (a) Write the

vector equation of this vector in terms of the unit vectors i,j, and k. (b) find the unit

vector of a vector B one forth the length of A pointing in the same direction as A.
i did part (a) i am stuck on (b)
thanks

 

[kronix6]

Hi. Can anyone solve this question for me . Iwould be grateful.

(i)Prove The Identity cos4x + 4cos2x = 8(cosx)^2 -3
(ii) Hence solve the equations for 0<x<360.

plz solve it with detail showing every important step. Thanks in advance.

 

[whitecorp]

A ball is thrown vertically upward and is caught at the same height 3 seconds later. Find (a) the distance it rose (b) the speed with which it was thrown .

There is symmetry involved here-the path of the ball on the way upwards, and that of the ball on the way downwards.
Let initial velocity of the ball be u, then time taken to travel upwards =3/2 =1.5s
When it attains its maximum height before falling downwards, velocity =0
Hence, 0= u + (-g)(1.5) =======> u=1.5g m/s (shown)
(Note that I have assigned upwards as being positive for the first half of the journey, therefore acceleration due to free fall aka g is defined in the negative sense.)
Also, 0^2 = u^2 -2(g)(s)
Substituting in (1): 0=2.25g^2 - 2g(s)
Solving gives s = 2.25/2 =1.125 g metres. (shown)

(Not sure if you use g =9.81 or 10 m/s^2, so I will leave it to you to stick in the appropriate value for both answers)

Hope this helps. Peace.

 

[whitecorp]

can someone please help me with some unit vector questions? I totally forgot how to do them again.


The vector A has x and y and z-components of 8, 12, and -4 units . (a) Write the

vector equation of this vector in terms of the unit vectors i,j, and k. (b) find the unit

vector of a vector B one forth the length of A pointing in the same direction as A.
i did part (a) i am stuck on (b)
thanks

Did you mean to say one fourth?

 

[whitecorp]

Hi. Can anyone solve this question for me . Iwould be grateful.

(i)Prove The Identity cos4x + 4cos2x = 8(cosx)^2 -3
(ii) Hence solve the equations for 0<x<360.

plz solve it with detail showing every important step. Thanks in advance.

Your identity is incorrect, the RHS should be 8 (cosx)^4 -3.
I have provided the solution for this:



For (ii), what equation exactly are you referring to? Note that (i) is an identity, there is nothing to solve for.

Peace.

 

[GorgeousEyes]

There is symmetry involved here-the path of the ball on the way upwards, and that of the ball on the way downwards.
Let initial velocity of the ball be u, then time taken to travel upwards =3/2 =1.5s
When it attains its maximum height before falling downwards, velocity =0
Hence, 0= u + (-g)(1.5) =======> u=1.5g m/s (shown)
(Note that I have assigned upwards as being positive for the first half of the journey, therefore acceleration due to free fall aka g is defined in the negative sense.)
Also, 0^2 = u^2 -2(g)(s)
Substituting in (1): 0=2.25g^2 - 2g(s)
Solving gives s = 2.25/2 =1.125 g metres. (shown)

(Not sure if you use g =9.81 or 10 m/s^2, so I will leave it to you to stick in the appropriate value for both answers)

Hope this helps. Peace.

Thanks a millioon , Helped me a looot

 

[whitecorp]

Thanks a millioon , Helped me a looot

No problem. Peace.

 

[Latifa]

Hi
how can i find IGCSE 2012 pastpapers for chem,physics and maths???
can any one help me p/zzzz!???
i need them urgentlyyy!!!

 

[asexamskillme111]

3^(x+2)=3^x+3^2

anyone?