Mathematics: Post your doubts here!

[faez932]

how to solve this question..my problem is i don't know how to draw a quadratic graph ( 4x^2-1 )
on a trigonometric scale.

use two equations y=4x^2-1 and y=cotx put values of pi/2 and pi/4 in place of x for both equations, draw sketches and show that both graphs cut at one point only

 

[vaishster]

(x/y)(dy/dx) + ln y = 2 .... convert this into -y/x^2

 

[IgoforA]

http://www.xtremepapers.com/CIE/Interna ... _qp_33.pdf q 10 part 2 b) solve it urgent and tq

 

[vaishster]

convert ln (cos 2x +1) / sin 2x = e^-2t ..... to tan x = (-1/2)(e^(-2t))

 

[mrpaudel]

http://www.xtremepapers.com/CIE/International%20A%20And%20AS%20Level/9709%20-%20Mathematics/9709_w10_qp_33.pdf q 10 part 2 b) solve it urgent and tq

p(z^2)=z^6 +mz^4+24z^2+32 and....the factor for this equation which can makes this zero are -1 -2 -4 -8 -16 and -32...so try these...are check whether this can b zero or not....!! this will reduce ur time...

 

[IgoforA]

what? so you mean you have to find the values to obtain zero.... i mean like you try 1 then 2 then3 then4 and so on....

 

[mrpaudel]

(x/y)(dy/dx) + ln y = 2 .... convert this into -y/x^2

i dont think this is possible...where's the = sign there?? it lost?

 

[mrpaudel]

what? so you mean you have to find the values to obtain zero.... i mean like you try 1 then 2 then3 then4 and so on....

that would b easy to do...since u have a last number as 32...so the factors of 32 are....1 2 4 8 16 and 32...also in the negative...however, the positive number cannot make that function zero..so try the negative ones...!! like..put -1 in place of z...and see if it makes the whole function zero..if it does....we can say (z+1) is the factor...!! that way

 

[vaishster]

(x/y)(dy/dx) + ln y = 2 .... convert this into -y/x^2

i dont think this is possible...where's the = sign there?? it lost?

dy/dx = -y/x^2 tats wat i meant

 

[IgoforA]

Okaysss tq... you're good dude... let's just hope that we're gonna do our best

 

[mrpaudel]

Okaysss tq... you're good dude... let's just hope that we're gonna do our best

Dude...i already got A in maths....!! i have biology tomorrow...!!

 

[mrpaudel]

(x/y)(dy/dx) + ln y = 2 .... convert this into -y/x^2

i dont think this is possible...where's the = sign there?? it lost?

dy/dx = -y/x^2 tats wat i meant

Well, i cannot solve any of those two....my knowledge is not enough..

 

[IgoforA]

waiiit.... do you have to square 32??? and you're retaking maths this nov?? woow

 

[mrpaudel]

waiiit.... do you have to square 32??? and you're retaking maths this nov?? woow

Well dude..without practising a single past paper.....A is gud..if i have practiced them all...have got A*......i wont retake...!! m reappearing biology...not maths....and...what 32 are u talking bout?

 

[IgoforA]

i mean p (z^2) = (z^3)^2 + 6(z^2)^2 + ... +32^2 <--------????

 

[mrpaudel]

i mean p (z^2) = (z^3)^2 + 6(z^2)^2 + ... +32^2 <--------????

no no...!! p(z) = .....................then..just we put p(z^2)= only..where there's z..!! not for the constant.!! we substituted z as z^2..thats it...!!

 

[PrecoiusPearl]

help me please
prove the identity
cosec x/ cot x+tan x = cos x

 

[mrpaudel]

help me please
prove the identity
cosec x/ cot x+tan x = cos x

u mean...cosecx/(cotx+ tanx) or (cosecx/cotx)+tanx??

Assalamoalaikum!!

She meant cosecx/(cotx+ tanx)

Well remember, for proving identities, always change the given in terms of sin and cos..and then simplify and change it to the required form..

cosec x = 1 / sin x

cot x = cos x / sinx

tan x = sin x / cos x

Now try solving it! If you really want to get better at this, I suggest trying it yourself...if u still dont get..I'll post it..but u must get it using the above conversions..
It's easier always to start from LHS and convert to RHS

 

[IgoforA]

http://www.xtremepapers.com/CIE/Interna ... _ms_33.pdf but the answers are different??

 

[mrpaudel]

ok...i think its cosecx/(cotx+ tanx)....so...do this way..

Cotx+tanx=cosx/sinx +sinx/cosx = sin^2x+cos^2x/Sinx.Cosx =1/Sinx.Cosx .

Now cosecx .sinx.cosx=cosx..hence proved