2 unit maths revision (2 Viewers)

[pwoh]

Safest method is do what harrisony does and write both unless otherwise stated in the question.
Definitely need to include exact value in your working but your teachers might want you to evaluate it ...

 

[cutemouse]

for the exact answer: = 63pi / 200

That's wrong :\

 

[ohexploitable]

That's wrong :\

This.

 

[MrBrightside]

That's wrong :\

well it matches the original decimal ans (approx ans) but if thats wrong, no one said anything, so yeah. anyone else going to attempt it?

 

[MrBrightside]

View attachment 22697

no one did this question, so I'll bump it.

 

[ohexploitable]

no one did this question, so I'll bump it.

lols, it's such an easy question and no one can be bothered

Everyone in this thread except you does 3/4U so yeah...

 

[ohexploitable]

cbf putting it into decimals, can't find my calculator...

 

[Bored Of Fail 3]

A= x sqrt (3600-x^2)

u=x
du/dx= 1
v= ( 3600 -x^2)^(1/2)
dv/dx= (1/2) ( 3600-x^2) ^(-1/2) x -2x = -x/ sqrt (3600-x^2)

therefore

dA/dx= sqrt (3600-x^2) - [x^2 / [ sqrt(3600-x^2) ] ]

set equal to zero for stat points

sqrt(3600-x^2) - [ x^2 / sqrt(3600-x^2) ] =0

multiply through by the denominator

3600-x^2 -x^2 =0
3600 -2x^2=0
x^2 = 1800
x= +- sqrt(1800) = +- 42.4

then check them, first derivative test is the easiest way to test

 

[MrBrightside]

A= x sqrt (3600-x^2)

u=x
du/dx= 1
v= ( 3600 -x^2)^(1/2)
dv/dx= (1/2) ( 3600-x^2) ^(-1/2) x -2x = -x/ sqrt (3600-x^2)

therefore

dA/dx= sqrt (3600-x^2) - [x^2 / [ sqrt(3600-x^2) ] ]

set equal to zero for stat points

sqrt(3600-x^2) - [ x^2 / sqrt(3600-x^2) ] =0

multiply through by the denominator

3600-x^2 -x^2 =0
3600 -2x^2=0
x^2 = 1800
x= +- sqrt(1800) = +- 42.4

then check them, first derivative test is the easiest way to test

I don't get that part, I know your trying to implement the power rule but where is your + Did you half of it in your head? I'm sorry, just looking at maths stuff in a text based way is a very hard way to learn.

 

[blackops23]

I don't get that part, I know your trying to implement the power rule but where is your + Did you half of it in your head? I'm sorry, just looking at maths stuff in a text based way is a very hard way to learn.

you don't get "that part"?? You mean the whole thing? Pretty simple, he just used a product rule to find the derivate, then let the derivative = 0...

 

[ohexploitable]

Product rule is unnecessary in this case, chain rule is much easier imo.

 

[SpiralFlex]

What questions are we doing guys?

Try this:

are the roots of the equation . Find equations whose roots are:

i)


ii)

 

[mitchy_boy]

ohexploitable, what TEX editor thingymajig do you use?

 

[hscishard]

I don't get that part, I know your trying to implement the power rule but where is your + Did you half of it in your head? I'm sorry, just looking at maths stuff in a text based way is a very hard way to learn.

"Power rule". Do you use understanding yr 11/12 maths?
I agree it is hard to read maths in this format. Try writing it out or something. Note the x's may be "times"
He didn't do much in his head. He worte nearly everything down

 

[ohexploitable]

ohexploitable, what TEX editor thingymajig do you use?

I don't use an editor, I'm pretty much fluent in TeX code.

 

[mitchy_boy]

Given that y=sin(x)cos(x), show that dy/dx=cos^2(x)-sin^2(x).

And hence find ʃ cos^2(x)-sin^2(x)/sin(x)cos(x)dx

 

[hscishard]

That can be done in less than 10 seconds with 3unit trig

 

[ohexploitable]

 

[mitchy_boy]

That can be done in less than 10 seconds with 3unit trig

yeh but it's a 2unit thread. just trying to help some of the kiddies on hear that aren't naturally talented at maths.

some people wouldn't automatically see that it turns into log, so i reckon it's a decent question, for reminding.

 

[Existential]

More detailed answers to questions and less bs bitching would be nice. Many ppl (myself included) just scim thru the pages in this thread. So yeah, full worked setting out is whats needed in this thread because its aimed at the pure 2 unit ppls, not the extension ppls... keep that in mind.