Q10a (1 Viewer)

[angmor]

shit...for q10a, could u have made (ln x)^3 = 3 ln x

and then go 3[lnx] to do simpsons rule for ln x, and then multiply that answer by 3 to get the answer?

 

[adamantium]

the Q is (ln x)^3
u bring the 3 down if its: ln (x^3)

 

[sando]

thats what i did.. no idea if its right ?

 

[meg_1_2_3_4_5]

yeah, i brought the 3 down the front and did it that way, but my teacher said that that was wrong cos it was (lnx)^3 not lnx^3. therefore it just had to be done normally, by cubing the function and the only reason it was in question 10 was because there were no odd ordinates because it was only 3 function values

 

[angmor]

so its wrong...

 

[meg_1_2_3_4_5]

yep. he said it might be the same answer and u still might get marks for stating simpsons rule and using the right values, but it is wrong.
he is probably only just saying that...........

 

[the pospinator]

ur teacher is right, u can't bring the 3 down

log laws show:

ln x^3 = 3ln x

(ln x)^3 does not = 3ln x

u might still get marks for working like correct use of simspons rule, but changing the answer to 3lnx is wrong

sorry

 

[meg_1_2_3_4_5]

i just read my last post and realised it didnt make sense. I meant that he was probably just saying that we might get marks for working to make me feel better.
I've always tried to prove him wrong...but he's always right.
anyways, must've been the 6 hrs and 10mins of exams i sat today that ruined my last chance of winning. dammit.

 

[Loz_metalhead]

Were we supposed to make ln 0.5 positive?

What answer did you get...I think I got it wrong

0.067

 

[matt88m]

Did anyone get 0.444 or somthing?

 

[shinji]

mmm
what formulae did every use?
did u use "h/3[a+l + 4[odd] + 2[even]" ??

coz i was doing 3u test today, found a similar-ish question
instead of using that formulae,
answers had:
h/3 [a + l + 4 ( [a+b]/2) ]

so yeah . .maybe that's why it was in q10~


i dnno, prove me wrong ppl here! coz i used the '4odd, 2even' formulae as well.


---
edit: found out the odd value = 0
so i got -0.444 or wateer

but i'll prob lose a mark for the wrong formulae~~

 

[abhi_89]

Did anyone get 0.444 or somthing?

yeah except you need a "minus" at the front ! .. the answer is -0.444

 

[kerfuffle]

But isn't Simpson's Rule a formula for finding the area? So you absolute value it to make it positive? O.O

 

[Triangulum]

But isn't Simpson's Rule a formula for finding the area? So you absolute value it to make it positive? O.O

Only when it specifically asks for area. It's a formula for estimating the value of an integration. The question said 'evaluate', so you don't use absolute values. It's like doing evaluating a definite integral.

 

[MoonLiteDreamz]

.. i kinda... absolute all the values.. hehe.. opps..

 

[kerfuffle]

Yeah, so did I.
There goes one mark.

 

[randomstudent]

i got -0.44

 

[dunno04]

arent we suppose to absolute value it?
I did...

 

[the pospinator]

u don't have to use absolute value, the qu asked for u to evaluate, not find the area, so the answer can be a negative

 

[Nesty]

yay. at least i know i got something for question 10