Mathematics: Post your doubts here!

[abcde]

how sinx = BC/AN ??

Why not? sin x = opp/hyp. The hypotenuse in this case is AN and the perp. would be the same as BC

 

[Silent Hunter]

oh sorry. silly me.....

 

[saimaiftikhar92]

CAN ANYONE HELP ME IN THE QUESTION FROM JUNE 2010 VARIANT 31 Q3???

I CANNOT UNDERSATND THIS ONE.....PLEASE HELP ME

THANKYOU IN ADVANCE...

 

[saimaiftikhar92]

PLEASEEEEEEEEE.......(

 

[abcde]

Please post the link of the question paper. One post for a single query is enough.

 

[saimaiftikhar92]

PLEASE HELP IN THE QUESTION I HAVE POSTED

 

[saimaiftikhar92]

http://www.xtremepapers.com/CIE/index.p ... _qp_31.pdf

 

[saimaiftikhar92]

PLEASE.... I HAVE GIVEN THE LINK ...QUESTION NO 3

 

[abcde]

(i) 1.10^n (5.20) = C
Use natural logarithm to form a linear equation in n and C:
=>n ln 1.10 + ln 5.20 = ln C
3.20^n (1.05) = C
=> n ln 3.20 + ln 1.05 = ln C
The two equations can now be equated:
n ln 1.10 + ln 5.20 = n ln 3.20 + ln 1.05
Rearrange the equation and you'll get n = 1.50 (correct to 3 sig. fig.)
Therefore, C = 3.20^1.50 (1.05) = 6.00 (3 s.f.)

(ii) n ln x + ln y = ln C
The graph of ln y against ln x would be a straight line as it has the above linear equation for ln y and ln x.
Hope you understand. If not, please review the properties of logarithms.

 

[saimaiftikhar92]

I GOT IT ..... THANKYOU SO MUCH

MAY I ASK YOU SOME MORE??????.....

 

[Muhammad Talha]

(iii) f(x) = k
=> 4 - 3 sin x = k
=> sin x = (4 - k)/3
sin x has values ranging from 1 to -1.
=> -1 ≤ (4 - k)/3 ≤ 1
=> k ≤ 7, k ≥ 1.
So for the function to have no solution, the ranges of k are: k > 7 and k < 1.

(iv)For g to have an inverse, it must be a one-to-one function (any horizontal line through the graph should intersect it at most once.From the sketch below, you can see that the greatest value would be 3 pi/2. If this value is exceeded, a horizontal line can cut the graph of g twice!

Thanx alot abcde......

 

[unique840]

(i) 1.10^n (5.20) = C
Use natural logarithm to form a linear equation in n and C:
=>n ln 1.10 + ln 5.20 = ln C
3.20^n (1.05) = C
=> n ln 3.20 + ln 1.05 = ln C
The two equations can now be equated:
n ln 1.10 + ln 5.20 = n ln 3.20 + ln 1.05
Rearrange the equation and you'll get n = 1.50 (correct to 3 sig. fig.)
Therefore, C = 3.20^1.50 (1.05) = 6.00 (3 s.f.)

(ii) n ln x + ln y = ln C
The graph of ln y against ln x would be a straight line as it has the above linear equation for ln y and ln x.
Hope you understand. If not, please review the properties of logarithms.

yar how can u say that we will use ln? cant we use lg? :%)

 

[saimaiftikhar92]

http://www.xtremepapers.com/CIE/index.p ... _qp_31.pdf

I NEED HELP IN QUESTION NO 2.... PLEASE.

 

[abcde]

(i) 1.10^n (5.20) = C
Use natural logarithm to form a linear equation in n and C.

yar how can u say that we will use ln? cant we use lg? :%)

Yes, you can! You'll get the same answer. Logarithms have the same properties whether it's the natural logarithm ln or the one to base 10. Just remember to use ln when you have an expression containing e^something. Since there's no such specification here, I think you can opt for lg.

 

[Silent Hunter]

How to solve this one?

a = 2sinx + cosx
b = 2cosx - sinx where x is from 0 to 360 (included)

show that a^2 + b^2 is constant for all values of x???

 

[abcde]

How to solve this one?

a = 2sinx + cosx
b = 2cosx - sinx where x is from 0 to 360 (included)

show that a^2 + b^2 is constant for all values of x???

AoA!
a^2 + b^2 = (2 sin x + cos x)^2 + (2 cos x - sin x)^2
= 4 sin^2 x + cos^2 x + 4 sin x cos x + 4 cos^2 x + sin^2 x - 4 sin x cos x
= 5 sin^2 x + 5 cos^2 x
= 5 (sin^2 x + cos^2 x)
= 5(1) = 5 (constant) =)

 

[saimaiftikhar92]

CAN ANYONE HELP ME TO SOLVE THIS EQUATION

Ln(1+X SQUARE)=1+2LnX

AND SECOND QUESTION IS:

USE LOGARITHMS TO SOLVE THE EQUATION 5^2X-1=2(3)^X , GIVING YOUR ANSWER TO 3 SIGNIFICANT FIGURES.

 

[sea_princess]

can someone help me with these questions:
1-Three letters are selected at random from the word SCHOOL.Find the probablity that the selection:
a)does not contain the letter O
b)contains both letters O

2-In how many different ways can a football team of 11 players be photographed if there are to be two rows ,with 5 seated on the front row and 6 standing in the back row?In how many of these photographswould the captain be sitting in the centre of the front row?
thanx in adavnce

 

[talhajohar]

solution for Ln(1+X SQUARE)=1+2LnX

 

[saimaiftikhar92]

I DID NOT UNDERSATND THE THIRD PART AFTER = SIGN