Mathematics: Post your doubts here!

[unique840]

f(x)= 6 (2x+3)^-1
f'(x) = -6 (2x+3)^-2 (2+0)
-12/(2x+3)^2
-[12/(2x+3)^2]
whatever the value of x, whether negative or positive, the whole square will make the entire bracket value positive. but the negative sign will always make the answer negative so f(x) is always a decreasing function.

 

[Silent Hunter]

f(x)= 6 (2x+3)^-1
f'(x) = -6 (2x+3)^-2 (2+0)
-12/(2x+3)^2
-[12/(2x+3)^2]
whatever the value of x, whether negative or positive, the whole square will make the entire bracket value positive. but the negative sign will always make the answer negative so f(x) is always a decreasing function.

How did you get the highlighted thing? I mean once we get f(x)= 6 (2x+3)^-1 we differentiate it and get f'(x) = -6 (2x+3)^-2 ? Why there is ^-2(2+0) ???

 

[unique840]

whenever we diffrenciate, first we diffrenciate the power as u did, thn we diffrenciate the term in the bracket

 

[unique840]

f : x → ....6
...............2x + 3

y = f(x)
f-1 ( y ) = x

y= 6/ 2x + 3
2xy +3y = 6
x= (6-3y)/2y

f-1(x)= (6-3x)/2x

markscheme says it is:
f-1(x)= −6(2x+3)^-2


checking through substituition in both the equation, I find equation in ms to be wrong,
Dunno!

markscheme says -6(2x+3)^-2 *2

 

[Anon]

stupid me. I saw it late... they put that 2 waayy ahead, never noticed.

 

[Silent Hunter]

I think o got my problem...I dont know how to differentiate in fractions.

Can anybody explain it? Please? (my maths exam is tomorrow)

Thank You

 

[Silent Hunter]

http://www.xtremepapers.com/CIE/International A And AS Level/9709 - Mathematics/9709_s09_qp_1.pdf

Q10 (ii)

 

[unique840]

http://www.xtremepapers.com/CIE/International A And AS Level/9709 - Mathematics/9709_s09_qp_1.pdf

Q10 (ii)

isnt it the same value as the value of b in part 1?
b,c are the turning points of the graph.. the line of symmetry is made at point b vertically

 

[unique840]

I think o got my problem...I dont know how to differentiate in fractions.

Can anybody explain it? Please? (my maths exam is tomorrow)

Thank You

jus bring the denominator in the numerator with negative power. and diffrentiate as u diffrentiate power and bracket as i stated above...

 

[alphabravocharlie]

jus bring the denominator in the numerator with negative power. and diffrentiate as u diffrentiate power and bracket as i stated above...

This guy is a good teacher, listen to him.

 

[unique840]

This guy is a good teacher, listen to him.

umm thanku but i m girl

 

[alphabravocharlie]

Sorry, let me re-phrase that, She is a good teacher, listen to her.

 

[elbeyon]

Please can anyone help me out with these questions ?

 

[unique840]

Sorry, let me re-phrase that, She is a good teacher, listen to her.

thanku

 

[unique840]

ans3) dy/dx = gradient
at that point, gradient is = 3/[1+2(1)]^2
= 1/3
equation is:
y-y1=m(x-x1)
y - 1/2 = 1/3 (x - 1)
3y - 3/2 = x - 1
3y = x + 1/2

 

[elbeyon]

Unique840 Thanks for helping me but I don't think that's the correct answer for that question.
Please someone help me.

 

[CaptainDanger]

Please can anyone help me out with these questions ?

Do you have the answers?

 

[elbeyon]

Yes CAPTAIN I have the final answers but I don't know the way to solve it. That's the problem.

 

[CaptainDanger]

Yes CAPTAIN I have the final answers but I don't know the way to solve it. That's the problem.

Tell me the answers... Let me try...

 

[elbeyon]

CAPTAIN these are the answers/instructions:-