Higher Maths 2012

Guys, any full explanation would be useful for this question. Heinemann Textbook EX15G Q4. All bases are 10

"The difference, n, in decibels, between two sound intensities is given by the formula n=10log(S1/S2), where S1 and S2 are the sound intensities in phons, S1>S2. Shuffling a pack of card has a sound intensity of 40 phons. If a clock alarm is 4 decibels greater than shuffling cards what is the sound intensity of the clock alarm?"

So tough. If anybody would be so kind as to give a detailed description I would be hugely grateful!

See in number 2? .. Why is it 1/3?

yeah I don't actually know why I just know you need to use these formulae

Well, differentiating e.g. y = sin(ax) using the chain rule. Let u = ax, then dy/dy = cos(u) and du/dx = a which gives us dy/dx = a.cos(ax). To find the antiderivative, you reverse this process, so you divide.

4=10log(S1/40)
0.4=log(S1) - log(40)
0.4 + 1.60 = log(S1)
10^2 = S1
S1 = 100

I think this works? Basically you substitute into the equation and then solve as normal.

Well the pressure is off for me because I performed well in my 1st three exams and I will hopefully do well in Biology as well so I think I have As for those 4 subjects. So my aim is to get a B in maths so I could end up with AAAAB which is very good and be able to do advanced higher maths next year.

Although looking at last years paper it appears to me pretty easy. WAY easier than the two prelims we doneso hopefully it'll be okay. I've not really started my revision yet and it's my birthday today. I'll do a few hours today, same tomorrow and then ramp it up on Sunday.

Good Luck.

Thanks. Also, going to sound daft...2009 Paper 1 q11? Can't figure out why it's 3? Any explanations?

Thanks. Also, going to sound daft...2009 Paper 1 q11? Can't figure out why it's 3? Any explanations?

Thanks. Also, going to sound daft...2009 Paper 1 q11? Can't figure out why it's 3? Any explanations?

I got stuck with that, but my teacher explained if root 9 = 3 then any number lower than root 9 the equation would have a solution

so (4 sin x – /5) would have 2 solutions and (sinx + 1) would be a negative so do the cast diagram and and it will only have one solution cause the negative would not count as a value so in total 3.

Hope that makes sense :P

Someone just posted on Twitter that it's %78 this year to get an A in Maths.. Please tell me this isn't true?

How would I do this question?

Solve log2(x + 3) + log2(x2 + 5x – 4) = 3.
(worth 5marks)
The red type is mean to be a base number
I tried it but i couldn't work it out properly, any ideas?

Is the answer x=-4 and x=-5 ?

Biology should be a good paper, I'm quite looking forward to it
Ooooft AH maths why would you
Have a good birthday and good luck with maths

According to the answer scheme it is x=1 or x=-4 or x=-5 (Stated explicitly here) Then it says for the final mark it should be x=1 only

According to the answer scheme it is x=1 or x=-4 or x=-5 (Stated explicitly here) Then it says for the final mark it should be x=1 only

Oh yeah x=1 too! Basically I worked out the log equation by multiplying the brackets by one another, i then changed it to an exponential so brackets = 8 and then used synthetic division using 1 as a factor.

If you have got to x= 1,-4,-5 what you have had to do is convert from logs to a quadratic equation. The solutions 1,-4,-5 are all correct for the quadratic but placing -4,-5 back into the original log equation, the first log ends up being log₂a negative. The log graph doesn't cover any value of x equal to or less than 0 so both of these(-4,-5) cannot be correct, so only x=1