Mathematics: Post your doubts here!

[DragonCub]

i hve anther doubt 2011 may/june Q4. ii

View attachment 5349
i dont understnd the formula for (ii)

With the gradient and a point, you can find the equation of the tangent.
Use differentiation to find the gradient:
dy/dx = -4/[3 (3x-4)^2]
at P, x =2, dy/dx = -4/[3 (3*2-4)^2] = -1/3 This is the gradient of the tangent at P.
Equation can be obtained:
(-1/3) (x - 2) = y - 2 , y = (-1/3) x + 8/3 OR x + 3y - 8 = 0

The tangent of the angle is the gradient of the tangent at P (too many "tangent"s maybe )
Angle = tan-1 (-1/3) = -30 deg

 

[Anonymous']

it's nothin i got u....
thnks....

i hve anther doubt 2011 may/june Q4. ii

View attachment 5349
i dont understnd the formula for (ii)

hmm..first, find dy/dx, which is dy/dx = -4(3x-4)^-2 (3) = -12(3x-4)^-2 (3) = -12/[(3x-4)^2]
then, at P, x = 2, sub x=2 in dy/dx, dy/dx = -12/[(3(2)-4)^2] = -12/4 = -3
therefore, equation of tangent : y = -3x + c, use the equation in the question to find the y-coordinate, that is, y = 4/[3(2)-4] = 2, next substitute P (2,2) in the equation y = -3x + c , which is 2 = -3(2) + c, therefore, c = 2 + 6 = 8
hence, the equation of tangent : y = -3x + 8

for part (ii) angle = tan-1 (-3) or tan-1 (3) as it passes through the x-axis, which means, there are four angles, i hope you understand this.. just imagine the line cuts the x - axis, there will be four angles, which are opposite to each other, which are tan-1 (-3) = -71.6 degrees or -1o8.4 degrees, or tan-1 (3) = 71.6 degrees or 108.4 degrees.. but, the question asks for angle, not angles, therefore, the answer can be one of the angles.. but for me, I would just show all the four angles, to be safe.. heheh.. I hope I give you all the workings needed.. heheh..

 

[RGBM211]

how to solve q7) iii)
9709/31/0/N/11

 

[Anonymous']

how to solve q7) iii)
9709/31/0/N/11

hmm.. what's the value of lambda that you got?

 

[Anonymous']

how to solve q7) iii)
9709/31/0/N/11

whatever the value of lambda that you got, substitute that value into moduli of AP, PB, OA and OB.. then, find the ratio of them..

 

[RGBM211]

I got lamda as 3/8

 

[RGBM211]

I did substitute but the rhs is not same as lhs

 

[Anonymous']

I did substitute but the rhs is not same as lhs

is that value of lamba correct?

 

[Sajjad Hossain]

I got a doubt can sum1 help me out its for 1 mark and i dont know how in the MS the answer is 90degree or 1/2pie
A function g is defined by g :

x → 3 − 2 sinx, for 0◦ ≤ x ≤ A◦, where A is a constant.

(iii)
State the largest value of A for which g has an inverse.

 

[RGBM211]

is that value of lamba correct?

YES chkd with mark scheme =)

 

[RGBM211]

I got a doubt can sum1 help me out its for 1 mark and i dont know how in the MS the answer is 90degree or 1/2pie
A function g is defined by g :

x → 3 − 2 sinx, for 0◦ ≤ x ≤ A◦, where A is a constant.

(iii)
State the largest value of A for which g has an inverse.

from which year paper is it ?

 

[Anonymous']

YES chkd with mark scheme =)

Hmm.. I think there's another way/method to find the ratio, but I forgot.. heheh.. I've already sat for my AS exam last year, so, I'm doing A2 now.. heheh..

 

[RGBM211]

Hmm.. I think there's another way/method to find the ratio, but I forgot.. heheh.. I've already sat for my AS exam last year, so, I'm doing A2 now.. heheh..

yu had paper 3 for A.S ?

 

[RGBM211]

DUDE ITS AN A2 QUESTION

 

[bamteck]

URGENT HELP PLEASE !

1. Given that 0<x<360, find all the values of x, to 1 decimal place, such that
(a) cos(x+30) = 0.6
(b) sinx + 2cosx + 0

2. Given that sin A = 3/5 and cos B = 4/√20, where A and B are acute. Find the value of tan A. cos A, sin B, tan B.

3. Given that cosec A = 7/2, where 90 < A < 180, find the exact value of sec A.


Thank You in anticipation =)

 

[leadingguy]

URGENT HELP PLEASE !

1. Given that 0<x<360, find all the values of x, to 1 decimal place, such that
(a) cos(x+30) = 0.6
(b) sinx + 2cosx + 0

2. Given that sin A = 3/5 and cos B = 4/√20, where A and B are acute. Find the value of tan A. cos A, sin B, tan B.

3. Given that cosec A = 7/2, where 90 < A < 180, find the exact value of sec A.


Thank You in anticipation =)

what are the ans. of this question?? or where u found them??? it will be easy to ans if u tell the ans. as well!~

 

[bamteck]

what are the ans. of this question?? or where u found them??? it will be easy to ans if u tell the ans. as well!~

Ans. 1 (a) 23.1 , 276.9
(b) 116.6 , 296.6

2. 3/4 , 4/5 . 1/√5 , 1/2

3. -7√5/15

 

[RGBM211]

URGENT HELP PLEASE !

1. Given that 0<x<360, find all the values of x, to 1 decimal place, such that
(a) cos(x+30) = 0.6
(b) sinx + 2cosx + 0

2. Given that sin A = 3/5 and cos B = 4/√20, where A and B are acute. Find the value of tan A. cos A, sin B, tan B.

3. Given that cosec A = 7/2, where 90 < A < 180, find the exact value of sec A.


Thank You in anticipation =)

here you go

 

[bamteck]

here you go View attachment 5461 View attachment 5462

Thank you very much bro =)

 

[shezi1995]

Can someone help me with this 1) solve to correct 3 siginificant figures e^x + e^(2x) = e^(3x)

2) Solve ln(x+2) = 2+Ln X

1)
-let e^x be y
-then separate e^(2x) and e^(3x) into (e^x)^2 and (e^x)^3 respectively
-replace e^x with y and solve for y
-use y=e^x to solve for x using only positive values or zero of y by ln(natural log) function or anyother indices method
2)
-2 is equal to ln(e^2)
-then combine ln(e^2) and lnx into one by using ln(ab)=lna + lnb
-functions inside ln(...) on both sides would be equall (i.e. in ln(a)=ln(b), a=b)
(p.s. I have not written the proper solutions because you should do it yourself otherwise it would not really benefit you)