Mathematics: Post your doubts here!

[Thought blocker]

can any one help me out in this question
Maths Paper 22 nov 11
question 1 plzz ASAP !!

Simple,
To remove modulus sign, square both the sides
you get,
(x^2 + 4x + 4) > (1/4x^2 - 2x +4)
Solve equation, you get:¬
3/4x^2 + 6x = 0
One root is -8 and other is 0
so -8 is -ve, x < 8 and x > 0

 

[Rutzaba]

In integration, when were determining the area or the volume and the range is following over both positive and negative values, do we have to divide the values into positive and negative sections? For example if the value are from -1 to 3, do we do f the area or the volume from -1 to 0 and 0 to 3 separately, or can we collectively find the area/volume from -1 to 3?

you dont do it separately

 

[sitooon]

thanks, brother.

Welcome

 

[saif mahmoud]

Simple,
To remove modulus sign, square both the sides
you get,
(x^2 + 4x + 4) > (1/4x^2 - 2x +4)
Solve equation, you get:¬
3/4x^2 + 6x = 0
One root is -8 and other is 0
so -8 is -ve, x < 8 and x > 0

ohh!!!!!
whats that lol im taking about igcse ol 0580

 

[saif mahmoud]

seems that i posted in the wrong thread

 

[Thought blocker]

seems that i posted in the wrong thread

IGCSE answer:
Total time 8 hours 30 minutes + first journey of 15 minutes that is total of 525 minutes.
So, bus leave port every 15 minutes, so in 525 minutes how many times did bus leave the port ? (do cross multiplication) that will end up to 525/15 = 35 times.

 

[saif mahmoud]

Great (Y)

 

[Haya Ahmed]

Can someone help me please
http://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Mathematics (9709)/9709_w10_qp_13.pdf

Q7(i)

 

[MiniSacBall]

Co-efficient of x in 1/x ,2/x, 12/x
And
http://papers.xtremepapers.com/CIE/...AS Level/Mathematics (9709)/9709_w05_qp_1.pdf
Q9 (ii) & (iii)

 

[Talha Khatri]

Can someone help me please
http://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Mathematics (9709)/9709_w10_qp_13.pdf

Q7(i)

We can see from the graph that it is quiet obvious that for the minimum possible value of the function, x=0
hence,
f(x) = 0.5 x^2 = 0.5 (0)^2 = 0

and for the maximum value of the function, x = 6
hence,
f(x) = 0.5 x + 1 = 0.5 (6) +1 = 4
so the range is 0 < f(x) < 6
The trick here is to use the right formula for the right value of x like for x= 0 you will use the first formula and for x= 6 you'll use the second one because they provided you with a domain that is to be used for each formula which is 0 to 2 for first and 2 to 6 for second.

 

[Haya Ahmed]

http://papers.xtremepapers.com/CIE/...S Level/Mathematics (9709)/9709_w10_qp_13.pdf

Q8ii please

 

[Haya Ahmed]

We can see from the graph that it is quiet obvious that for the minimum possible value of the function, x=0
hence,
f(x) = 0.5 x^2 = 0.5 (0)^2 = 0

and for the maximum value of the function, x = 6
hence,
f(x) = 0.5 x + 1 = 0.5 (6) +1 = 4
so the range is 0 < f(x) < 6
The trick here is to use the right formula for the right value of x like for x= 0 you will use the first formula and for x= 6 you'll use the second one because they provided you with a domain that is to be used for each formula which is 0 to 2 for first and 2 to 6 for second.

Ohh thanks bro

 

[ZaqZainab]

http://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Mathematics (9709)/9709_w10_qp_13.pdf

Q8ii please

Find the total length from AC using sin rule
sin(1.2)/AC=sin(0.6)/5
AC=8.25
we know PC and AQ are 5 cm so
10-8.25=1.75
there is another way given in the MS but i prefer this way

 

[kitkat <3 :P]

http://papers.xtremepapers.com/CIE/...S Level/Mathematics (9709)/9709_w12_qp_12.pdf
Q1 ii) and Q7 please
m not good with vectors

 

[sudeep1097]

Thanks soo much bro ,
Got a doubt, why direction vector is
( 1'0'0) why the 1 is it alwaya 1 when
Parallel to x-axis?
When i squared both sides, didnt get
X=y
Thanks again

Sorry about the x=y .
|z-3|=|z-3i|
now removing modulus sign we get sq rt of ((real component)^2+(imaginary component)^2) on both sides
suppose z as x+yi you get sq rt of ((x-3^2)+y^2)=(x^2+(y-3)^2)
remove sq rt by squaring both sides now solve to get x=y

yeah vector parallel to x axis is always (1,0,0) for y axis (0,1,0) and z axis (0,0,1) remember this
as (1,0,0) lies in x-axis and line which lies on a bigger line is parallel to it. These are the most simple vectors parallel to respective axis, there are others as well but use this !

 

[Snowysangel]

you dont do it separately

So well get the same answer if we find the area collectively? Doesn't the negative sign reduce the total area?

 

[xyn1123]

9709/31/o/n/13
Help!

 

[Rutzaba]

So well get the same answer if we find the area collectively? Doesn't the negative sign reduce the total area?

no

 

[Faaiz Haque]

Q1)? http://papers.xtremepapers.com/CIE/...AS Level/Mathematics (9709)/9709_s07_qp_1.pdf
I don't get it, someone please help.

 

[SitiPutri]

Q1)? http://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Mathematics (9709)/9709_s07_qp_1.pdf
I don't get it, someone please help.

y = 2x + c and y^2 = 4x
x = (y-c)/2 and x = y^2/4

Since the line is a tangent to the curve, then (y-c)/2 = y^2/4. And then you'll get 2y^2 - 4y + 4c.
Their discriminant must be equal to zero.
Thus, 16 - 32c = 0 -> c = 16/32 -> c = 1/2