Mathematics: Post your doubts here!

[omaaaar]

Suppose you extend a line starting from d to ab il call this peter
suppose you extend yet another line from e to ab il call it david
now luk at the diagram u will find peter=david (they are twins )
now if peter = david then if we find peter we will get david...
to find peter we need the fbi kidding lol
we have a theta=pi/3 and a hypotenuse 6
so sin= opp/hyp
sin pi/3= peter/6
peter= 6 sinpi/3
6*(root 3)/2 = peter
peter= 3 root 3
since this is also equals to david
david again can be found by sin=opp/hyp
just in this case the hyp is 10 and the theta theta
sintheta= opp/hyp
sintheta=david/10
sintheta=3 root 3/10
theta= sin inverse of (3 root 3)/10
rememb me in ur prayers ^_^

Thanks

 

[Rutzaba]

Why does F(x)=(2x^2) -8x+5 for the domain 0<equal x <equal 5 does not have an inverse? What are the conditions for an inverse?

ssimple one line answer... its a one to one function...
haina? SalmanPakRocks ?
yahi hota hai na?

 

[Rutzaba]

Thanks

np

 

[princeali97]

ssimple one line answer... its a one to one function...
haina? SalmanPakRocks ?
yahi hota hai na?

Pls read the question -_____________- "

 

[sudeep1097]

Sorry for disturbing you again
Got other doubt , when you square
right hand side you get x^2 + ( iy-3i)^2
which dont simplify to x=y when solve
and on what basis did you square root ,
Is this also a rule in complex no.

ohh there is a derivation for the square root. But it's not necessary all you need to remember is removing modulus sign in complex number means square root of (real number ^2 + coefficient of imaginary number ^2) don't include i.
You made that mistake don't include i after you square root it! ( that is after you remove modulus)

 

[Rutzaba]

Why does F(x)=(2x^2) -8x+5 for the domain 0<equal x <equal 5 does not have an inverse? What are the conditions for an inverse?

i did read the question...
any function that is a one to one function doesnt have an inverse...
you make a graph of this
and then when you see for every one value of x there is one value of y then its one to one...
if there is more than one to one then it doess have an inverse

 

[Haya Ahmed]

10 (ii)g(x)=4x^2 -24x +11 with domain x ≤ 1
Substitute 1
4-24+11=-9
but how do we know if its ≤ or ≥
The domain says x is less than 1 so x can be 0
Substitute 0
11
Which is more than -9 so f(x)≥ -9
iii) you do completing the square
4x^2 -24x +11 ----> 4(x-3)^2 -25 =y
make x the subject
3+- 0.5 root of (y+25)/4= x
we have to remove the +- to do that look at the domain if it says x≥ hen we use + if it says x≤ then we use - 3- o.5 root of (x+25) = g(x) inverse
the range of g(x) is the domain of g(x) inverse
x≥ -9
6(ii) fg(x)=1= 0.5(cosx) + pie/6
make cosx the subject
cox=(1-(pie/6) )*2 =0.952
x= cos inverse of 0.952 make sure your calculator is in radians mode
x=0.31 you can also get 5.97 but that does'nt come in the range
8(ii) you have show that it has a stationary point at x=-1
dy/dy = 2(3x+4)^3/2 - 6x - 8
substitute -1
2(-3+4)^3/2 +6 -8 =0
hence proved dy/ dx at x=-1 is 0 that is its stationary point
and now determine its nature find the derivative of derivative
which is= 3(3x+4)^1/2 (3) -6
substitute -1
= 9-6= +3 which is a positive value and the point it Minimum
(iii) Integrate dy/dx
you get
y=((4(3x+4)^5/2 )/15) -(3x^2)-(8x)+c
substitute y=5 and x=-1 you get c as -4/15

Thanks alot but there some small problems ..
( we have to remove the +- to do that look at the domain if it says x≥ hen we use + if it says x≤ then we use - ) I didn't understand what you mean by this can you explain it in details please


and for Q6(ii) I also got 0.31 but in ms it is given +-0.31 ? from where "-" came ?! ..

and for Q8(iii) It is given in the ms C =5 however I got it -4/15 too !!

 

[princeali97]

What are u saying? this is the question: STATE THE SMALLEST VALUE OF P FOR WHICH F IS ONE-ONE.

 

[jrahmed]

Dy/dx= -0.6xy

X=5e^-3t

T=0 y=70

Put y into the eq of dy/dt
- Is a minus ok?
Dy/dx= -0.6y(5e^-3t)
Dy/dt=-3ye^-3t
Putting the ts on one side aND the y on other
Dy(1/y)= dt -3e^-3t
Integrate both sides to remove the d
Lny= (-3e^-3t)/-3
ny=e^-3t +c
Wen t=0 y=70
Ln70= 1+c
C=ln70-1
Putting it bak into eq
Lny=e^-3t +ln 70 -1
Lny-ln70=e^-3t -1
By log property
Ln(y/70)= (e^-3t ) -1
y/70= e^((e^-3t)-1)
y=70 e^((e^-3t)-1)

thanks a ton

 

[Rutzaba]

What are u saying? this is the question: STATE THE SMALLEST VALUE OF P FOR WHICH F IS ONE-ONE.

plz read the question again.

 

[Talha Khatri]

Can someone please answer this questions about As Math ( P1 & M1 )
i am a private candidate and I am a bit confused about the Answer Booklet/Paper,
how many pages it will be?
does it have a limited pages ?
can i solve questions randomly e.g ( solve last question first )
In mechanics do i have to draw a diagram?

Any help would be appreciated.

There are about 15 to 20 pages in one booklet as far as I remember and you are allowed to ask for as many booklets as you desire, in the end they'll provide you a clip that attaches all the booklets together and you just have to make sure to attach them in the right order.
As for the questions I believe that you can answer in any order as you prefer just remember to write down the question number and part accurately.
Yes, in mechanics it is highly encouraged that you make diagrams that are well labeled and atleast clearly illustrated, however don't start wasting your time trying to replicate Picasso or Da Vinci making life like structures and stuff. (Joke tha hass lo ) So in short, be quick and draw just enough things that what you are doing is clear to the examiner. One more thing, you should write down formulas before substituting the values into them like first write down, 0.5mv^2 for kinetic energy and then input the values. If you need to ask any further questions feel free to ask here so that others can benefit from it too

 

[Relon]

There are about 15 to 20 pages in one booklet as far as I remember and you are allowed to ask for as many booklets as you desire, in the end they'll provide you a clip that attaches all the booklets together and you just have to make sure to attach them in the right order.
As for the questions I believe that you can answer in any order as you prefer just remember to write down the question number and part accurately.
Yes, in mechanics it is highly encouraged that you make diagrams that are well labeled and atleast clearly illustrated, however don't start wasting your time trying to replicate Picasso or Da Vinci making life like structures and stuff. (Joke tha hass lo ) So in short, be quick and draw just enough things that what you are doing is clear to the examiner. One more thing, you should write down formulas before substituting the values into them like first write down, 0.5mv^2 for kinetic energy and then input the values. If you need to ask any further questions feel free to ask here so that others can benefit from it too

Thank you very much, really helpful information.

 

[princeali97]

i have a question .........http://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Mathematics (9709)/9709_s12_qp_13.pdf...... q1(ii) try,Is my working enough?

 

[Thought blocker]

Best method for question 1 may/june -10 paper 11

 

[Talha Khatri]

ssimple one line answer... its a one to one function...
haina? SalmanPakRocks ?
yahi hota hai na?

Actually, a function has to be one to one in order to have an inverse so if it isn't one to one, it does not have an inverse.

 

[SalmanPakRocks]

ssimple one line answer... its a one to one function...
haina? SalmanPakRocks ?
yahi hota hai na?

Yup/

 

[Rutzaba]

Actually, a function has to be one to one in order to have an inverse so if it isn't one to one, it does not have an inverse.

ohh yeah explain the kid plz

 

[Talha Khatri]

i have a question .........http://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Mathematics (9709)/9709_s12_qp_13.pdf...... q1(ii) try,Is my working enough?

You technically copied what was written in the mark scheme. I would write something like this:
tan^2@ - sin^2@ is always greater than zero for the values of theta between 0 to 90. Hence,
tan^2@ - sin^2@ > 0
tan^2@ > sin^2@
tan@ > sin@
Now that I think about it, you did write everything that is required plus it is just worth one mark so you aren't expected to do much working. So that should be enough

 

[princeali97]

ohh yeah explain the kid plz

U guys have misread the question!I know that a function has an inverse when it is one-one only.But if u click this God-damn link and see q8(iii) you eyes will see that the question is "STATE THE SMALLEST VALUE OF P FOR WHICH F IS ONE-ONE.http://papers.xtremepapers.com/CIE/...S Level/Mathematics (9709)/9709_s12_qp_11.pdf

 

[Rutzaba]

U guys have misread the question!I know that a function has an inverse when it is one-one only.But if u click this God-damn link and see q8(iii) you eyes will see that the question is "STATE THE SMALLEST VALUE OF P FOR WHICH F IS ONE-ONE.http://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Mathematics (9709)/9709_s12_qp_11.pdf

calm down swt hrt...
u posted one question then sumone replies then u post another question so u wait fr sum to read it yeah hunz?