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core maths c12 10 jan 2017

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My value for volume was 800 something.I found the sum of one and multiplied by 20


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t was log 5/log 3
There were 3 x-values but log can only be used with positive number and there was only 1 positive value.


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In trignometry part b there was (Thita , 10°) on both LHS and RHS did these get cancelled how were they used?
1.3 and 91.3 degrees were the only possible solutions.
Original post by OnTheHorizon
t was log 5/log 3
There were 3 x-values but log can only be used with positive number and there was only 1 positive value.


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Same
Original post by Hammadjawaid12
Sumayya how did you get that value for volume First term a=180 r=0.93 n=20 by inputing these in sn formula we get1969.1


Actually the sum of the litres for the first barrel was around 602 but then they said that every year a new barrel is filled and it increases by the same common ratio so i found the sum of litres of the first 3 to 4 barrels and they formed a new geometric series so i found the new r which was 1.1 and my a was 602 and n was 20
Original post by Sumaiyya1999
Actually the sum of the litres for the first barrel was around 602 but then they said that every year a new barrel is filled and it increases by the same common ratio so i found the sum of litres of the first 3 to 4 barrels and they formed a new geometric series so i found the new r which was 1.1 and my a was 602 and n was 20


Well damn there goes my 3 marks straight out the window.
Original post by mr.holmes
that is what i did for the trigonometry question but i think you will lose solutions.
i did a similar question in a previous year and i divided by tan and i actually lost 2 solutions.
could you please tell me how you found your answer for the geometric question?
and what was the value for t


No i didnt divide by tan i just brought the cos on the rhs and it came in the form 5sintheta/costheta so I equated tan in place of sin/cos to give 5 tantheta
The question where we were supposed to express log3 (x/9) and log3 (√x) in terms of y, what answers did you guys get? I got the same answer for both and that was y/2.
Original post by Hammadjawaid12
In trignometry part b there was (Thita , 10°) on both LHS and RHS did these get cancelled how were they used?


Nope Khan bhai
Original post by Sumaiyya1999
No i didnt divide by tan i just brought the cos on the rhs and it came in the form 5sintheta/costheta so I equated tan in place of sin/cos to give 5 tantheta


sorry i meant dividing by cos
Original post by Hammadjawaid12
In trignometry part b there was (Thita , 10°) on both LHS and RHS did these get cancelled how were they used?

No they became tan(theta+10) so when u solve u minus the 10 from all the values of theta
Original post by Fasih178
The question where we were supposed to express log3 (x/9) and log3 (√x) in terms of y, what answers did you guys get? I got the same answer for both and that was y/2.


For the first one i got y-2 and 2nd i got y/2
Original post by mr.holmes
sorry i meant dividing by cos


I did that in alot of papers and didnt lose any value
Original post by Sumaiyya1999
For the first one i got y-2 and 2nd i got y/2


Thank God. I thought I messed up cuz it's quite unusual to get the same answers for two different questions.

For the log equation in part B I got x=81. I'm guessing the answer is probably correct since the answer to part A is correct as well.
Original post by Sumaiyya1999
I did that in alot of papers and didnt lose any value


i dont know. Anyways, i did the question in two ways in the exam so hopefully they will correct the right one. one of the ways is that i squared all the terms.
The ans for the part a wasnt y/2 it was y - 2 and after solving i got 3 for y and 27 for x

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There are usually more than one ways of doing a question i hope we both get it right

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The only situation where you can lose a solution or two is when you divide by a trig function by some other trig function and cancel them out, when instead you were supposed to factorize a common trig function out but that wasn't the case in the trig question we got.
i got 2 values for y since it will be a quadratic equation. i basically solved it by substitution since the gave as the what is Y is equal to.

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