#1
hey guys,
just cam back from uni. had a test which is like 15% of my cw. pretty confident but just some question that if you can confirm i got right that'll be great.

1) integration by substitution between x=o (lower limit) and x=1 (upper limit). Did anyone get 6?

2) can;t remember exactly by if you have something like , to find dy/dx will you just use the quotient rule to find the first part and then "+ 2"?

thanks
0
10 years ago
#2
I could be wrong, but I think:

1) Answer = (8/3)*2^(3/2). After integrating, I got (8/3)(x^2+1)^(3/2) -- what did you have?

2) You could use the quotient rule, but it would be a bit pointless. Just differentiate the numerator, then divide it by 2.
0
10 years ago
#3
(Original post by Prokaryotic_crap)
hey guys,
just cam back from uni. had a test which is like 15% of my cw. pretty confident but just some question that if you can confirm i got right that'll be great.

1) integration by substitution between x=o (lower limit) and x=1 (upper limit). Did anyone get 6?

2) can;t remember exactly by if you have something like , to find dy/dx will you just use the quotient rule to find the first part and then "+ 2"?

thanks

There is no need to use the quotient rule on the second question (although you should have got the correct answer even if you did).

0
10 years ago
#4
Oops garbage, damn internet lol. Ignore this post please
0
10 years ago
#5
I got the answer as (16*sqrt(2))/3 - 8/3 for the first one
0
#6

Unparseable or potentially dangerous latex formula. Error 4: no dvi output from LaTeX. It is likely that your formula contains syntax errors or worse.
8(u -1)^\frac{1}{2} u^\frac{1}{2} \frac{du}{2(u-1)^\frac{1}{2}
simplyfying that and subbung u=2 and u=1 and then taking the latter from the former will give 6 i'm sure. anyone who disagrees please post working. it'll really help.
0
10 years ago
#7
u = sqrt(1+x^2), udu/dx = x, dx = u/x * du substitution into the integral and you get 8u^2 du to integrate and your limits become u=1 to u = sqrt(2)
0
#8
i have just realised my mistake, and to make things worse i have just realised that i had written the right thing and then just crossed it out and written something else. I want to kill myself right now
0
10 years ago
#9
PC,

This is what it should have looked like.

I'm sure you can finish it off.
0
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