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[Ulti]

okay ken this one's for you

take the indefinite integral of: x(x+4)^1/2

the answer is (2/5)(x+4)^(5/2) - (8/3)(x+4)^(3/2) + c

these are usually pretty easy but I dunno how the fuck the book got that answer.
so far all I have is that
u = x+4
du = 1

I tried having u = (x+4)^(1/2) then du be (1/2)(x+4)^(-1/2) but that doesn't seem to work either.

[edit] okay I got a little further.
u = x + 4
x = u - 4

so I have (u-4)(u)^(1/2)

stuck again!

Ahaha. I am in the same position at my calc class. But the problems I get screwed on are friggen harder. Its easier to use Integration by Parts but it looks like you are asked using Integration by Substitution. Which is stupid. It should be solved using Parts. Substitution is a bitch to use in this case. It could be a substitution and a parts.

integral (u - 4 )(u)^1/2

w = u - 4
dv = u^1/2
dw = dx
v = 2/3 u^3/2

(u - 4)( 2/3 u^3/2) - integral ( 2/3 u^3/2 dx)

which gives us:

2/3 u ^5/2 - 8/3 u^3/2 - 4/15 u^5/2

which is

2/3 (x + 4)^5/2 - 8/3 (x + 4)^3/2 - 4/15 (x + 4)^5/2

I'm on the right track. It is a substitution and parts problem. I think the issue is early on, picking what u is. I'm gonna give it a few more whirls.

 

[Gatorade]

Alright I have to do a Chemistry lab report and I am really confused on one of the questions. We dissolved solid NaOH in HCl and we recorded the initial and final temperature of the solution and calculated the change in temperature (T final- T initial) and it was 9.3 degrees Celsius. The question states:

Calculate the experimental enthalpy change of this reaction in kJ per mole of NaOH.

What do I do to find this?

 

[stephaknee]

Ahaha. I am in the same position at my calc class. But the problems I get screwed on are friggen harder. Its easier to use Integration by Parts but it looks like you are asked using Integration by Substitution. Which is stupid. It should be solved using Parts. Substitution is a bitch to use in this case. It could be a substitution and a parts.

integral (u - 4 )(u)^1/2

w = u - 4
dv = u^1/2
dw = dx
v = 2/3 u^3/2

(u - 4)( 2/3 u^3/2) - integral ( 2/3 u^3/2 dx)

which gives us:

2/3 u ^5/2 - 8/3 u^3/2 - 4/15 u^5/2

which is

2/3 (x + 4)^5/2 - 8/3 (x + 4)^3/2 - 4/15 (x + 4)^5/2

I'm on the right track. It is a substitution and parts problem. I think the issue is early on, picking what u is. I'm gonna give it a few more whirls.

Thanks, I figured it out (you lead me in the right direction!) Answer, in case you were wondering:

u= x+ 4
x = u-4

(u-4)(u)^1/2

g=u^(1/2)

(u-4)(g) = (gu) -4(g)
= (U^1/2)(u) - 4(u)^1/2
=(u)^(3/2) - 4(u)^(1/2)
= 2/5u^(5/2) - 8/3u^3/2
=(2/5)(x+4)^(5/2) - (8/3)(x+4)^(3/2)

 

[Ulti]

Hm. That is a pretty new way to solve the problem for me. I think I am missing a step <<' Oh well. Tutor will crank out all my issues. Glad I could help you :3

 

[Nostalgia]

In all honesty, Gatorade, we need 2 threads. Look at how busy it gets.

 

[Gatorade]

In all honesty, Gatorade, we need 2 threads. Look at how busy it gets.

This is why I posted my question in both threads and got no response in either lol. But I figured out the answer to it on my own, but now I need to find out the thermodynamic equation for the same problem, including the enthalpy.

Edit: I got NaOH (s) + HCl (aq) -> H2O (l) + NaCl (aq) change in H = 160 kJ

Does anyone know if this is correct? I'm not sure if I gave enough info. If I didn't, let me know what I omitted and I will add it.

 

[Vayne Mechanics]

okay ken this one's for you

take the indefinite integral of: x(x+4)^1/2

the answer is (2/5)(x+4)^(5/2) - (8/3)(x+4)^(3/2) + c

these are usually pretty easy but I dunno how the fuck the book got that answer.
so far all I have is that
u = x+4
du = 1

I tried having u = (x+4)^(1/2) then du be (1/2)(x+4)^(-1/2) but that doesn't seem to work either.

[edit] okay I got a little further.
u = x + 4
x = u - 4

so I have (u-4)(u)^(1/2)

stuck again!

My university went on strike so I don't know integrals hun ): There's roughly a 2.5 month span between the stuff you know and the stuff I know.

 

[Nostalgia]

Here are two that I'm having trouble simplifying because I suck at factoring (I knew it would come back to bite in the ass someday).

x^2n + 2x^ny^n - 3y^n
x^2n + 5x^ny^n + 6y^2n

I factored the top to be (x^n + 3y^n)(x^n - y^n) and the bottom to be (x^n + 3y^n)(x^n + 2y^n).

So, now I have:

(x^n + 3y^n)(x^n - y^n)
(x^n + 3y^n)(x^n + 2y^n)

Then, it cancels to be...

(x^n - y^n)
(x^n + 2y^n)

Is this correct?

(I'll type the other one later).

 

[Vayne Mechanics]

x^2n + 2x^ny^n - 3y^n
x^2n + 5x^ny^n + 6y^2n

Your notation is horrible. How does an exponent have an exponent?

See: 2x^ny^n

But anyway, it's correct.

 

[Azrael]

Here's a problem that I really don't know

4/3 X pi x radius powered to the three = volume

Solve for r in terms of V

 

[▽]

Here's a problem that I really don't know

4/3 X pi x radius powered to the three = volume

Solve for r in terms of V

divide by 4/3. Dividing fractions is done by multiplying it's inverse, in this case 3/4. This give (3/4) x v = pi x r x r^3. Divide both sides by pi, which is equal to multiplying with 1/pi giving you r^3 = (3v)/(4 x pi). Now it's just taking the cube root so r = cube root((3/4 x pi) x v).

 

[Swift]

Nid help...

Solve each pairs of simultaneous equations...

y(x+2) =2y+ 2x .....(i)
x-x/2=0 .....(ii)

 

[▽]

y(x+2)=2y+2x

writing out

xy+2y=2y+2x

subtract 2y from both sides

xy=2x

divide both sides by x

y=2 for any x

It's the only solution i found. Normaly nonlinear equations are in the form of ax+by=q and cx-dy=r with the letters a,b,c,d,q and r being given numbers.

 

[Nostalgia]

Would someone be able to explain to me what a factorial is?

Actually, I get what it is, but more so I'd like to see how it's used.

 

[Aucune Raison]

Factorial is the product of all positive integers less than or equal to n, so if you have !5, it would go
5*4*3*2*1=120

It's used for probability for permutations and the like.

 

[Castillo]

Although Frieda is typically very reserved, as part of a huge rock concert crowd she lost her inhibitions and behaved in a very sexually provocative way. Frieda’s unusual behavior is best understood in terms of:

[FONT=Verdana, Arial, Helvetica, sans-serif]a. the bystander effect.[/FONT]
[FONT=Verdana, Arial, Helvetica, sans-serif]b. social facilitation.[/FONT]
[FONT=Verdana, Arial, Helvetica, sans-serif]c. deindividuation.[/FONT]
[FONT=Verdana, Arial, Helvetica, sans-serif]d. the mere exposure effect[/FONT]

 

[Aucune Raison]

B seems the most likely, but don't take my word for it.

You cheater you.

EDIT Actually, C seems to be it.

 

[Mastermind]

I was leaning toward B and C, but toward B more. However, I looked it up on Wikipedia (It's not totally unreliable) and deduced that it was C and it makes sense. She lost her sense of self so to speak. Don't you just love psychology?

 

[Home bound]

Psych is my major.

 

[giggleyroxas]

Ax^2+Bx+C=0

I need to show my teacher how to Complete the square and find x, DOES NOT NEED SOLVED, I just need show how to complete the square and find x.