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1. Acid's and Bases

Homework Statement I was asked to calculate the pH of .40M solution of NH4ClO4 but I wasn't given a Ka for it. Homework Equations The Attempt at a Solution I dissciated NH4ClO4 into: NH4(plus) and ClO4(minus) but I"m stuck there. What am I doing wrong?
2. Impossible problem?

Thats the equation I was given.
3. Impossible problem?

you're right its 12 but how can I solve the problem?
4. Derivative Problem

Homework Statement What's the 39th derivative of cosx? Homework Equations 1st dy/dx: -sin x 2nd: -cosx 3rd: sinx 4th; cosx The Attempt at a Solution So it repeats every 4 so I used 39/4 and for a remainder of 3 so is is the 3rd one down? I got sin x but I don't know...
5. Impossible problem?

Homework Statement is( X^2 )y + (Y^2)x = 6, then the second derivative at the point (1,3) is ? Homework Equations The Attempt at a Solution I don't see how this is possible, when I plug in 1 and 3 it comes out as 9 = 6 which isn't true. Can someone tell me if this is wrong? or...
6. A piece of iron weighing 85.65 grams was burned in air.

Homework Statement A piece of iron weighing 85.65 grams was burned in air. The mass of the iron oxide produced was 118.37g. 1. Use the law of conservation of mass to calculuate the mass of oxygen that reacted with iron. 2. use the molar mass of oxygen to calculate the number of moles...

Negative.

9. Line spectrum problem

Homework Statement Radiation with the wavelength 5.0x 10^-6 Meters belongs to what region of the spectrum ? Homework Equations None really. The Attempt at a Solution I don't really know how to read the spectrum too well, but it looks like Infared, am I right?
10. Chemistry question

Homework Statement A carbon-Oxegen double bond in certain organic molecules absorbs radiation that has a frequency of 6.0 x 10^13 s^-1 A. What is the wavelength of this radiation? B. What is the energy of this radiation per photon? per mole of photons? Homework Equations The Attempt at a...
11. Simple probem check

Yes, I did that and sin ^2x + Cos ^2X = 1 so that leaves me with sin^2x - cos^2x, which I have to simplify. I turned that into (- cos^2x + Sin^2x) for simplification purposes. Then I multiplied that whole thing by -1/-1 Which gave me Cos ^2x - Sin ^2x, which simplifies to Cos 2x...
12. Trig identities

x = pi/6 + 2kpi, 5pi/6 = 2kpi? On a test or something, would I just leave the answers as so? ( if their correct).
13. Word Problem ! Beginning Calculus

1. Homework Statement [/b] A cyclist is riding on a path modeled by f(x)= 0.08x where f and f(x) are measured in miles. Find the rate of change in elevation when x = 2 Homework Equations (f(∆x + x ) - f(x))/∆x ∆x\stackrel{lim}{\rightarrow} 0 The Attempt at a Solution I...
14. Problem Check

Definitely ! Thanks.
15. Problem Check

SO my final answer will be: pi/4 + 2pi/4? How would I do this for a repeating angle such as: sin x = -1/2 or 1/2 with no limits? since the difference are different. Like pi/6, 5pi/6, 7pi/6. The differences are different.
16. Problem Check

OH, so for this specific problem I'm going to write: pi/4, 3pi/4, 5pi/4, 7pi/4, + pi/2? In that order?
17. Problem Check

How do I list every spot where tan = 1 or -1? without actually "listing" them all out.
18. Problem Check

Homework Statement Tan^{2}X - 1 = 0 Homework Equations The Attempt at a Solution I added 1 to both sides, then I took the square root of both sides giving me: tan x = \pm1 which gives me answers at pi/4, 3pi/4, 5pi/4 and so on. Do I just write pi/4 + 2kpi as my answer?
19. Trig identities

No limits. So my answer is basicaly, 30 degrees or pi/6 + 2kpi? Correct?
20. Arcsin x sin

so in this case would it be arcsin(sin(60)) = Arcsin ((\sqrt{3}/2 ? Can you give me a problem that displays what you have just told me? I'd really like to see one ( as I have not been told that in my Precalculus class). Thanks.
21. Trig identities

yeah, its pi/6, 5pi/6, and so forth. Whats the sign that I add to the answer if it's periodical? How exactly do I write the answer for this problem? Do I write all the radians that make the equation true one time around the unit circle then add the (periodical)?
22. Simple probem check

Thanks, I guess I just have to memorize that. Thank you !
23. Arcsin x sin

Oh I think I get it. So, I can take the arcsine of both sides in a problem such as: sin(2x) = (Root3 )/2 and I would get arcsin(sin(2x)) = arcsin ((root3)/2) Which would get me to 2x = arcsin ((root3)/2)? Correct?
24. Arcsin x sin

Homework Statement arcsin(sin) = 1 right? Homework Equations The Attempt at a Solution Basically, I see arcsin as 1/sin is this correct?
25. Simple probem check

I understand from the point of a variation of the double angle formulas, but can you expliain your reasoning a bit to me? I get two different answers from two different methods. It worries me hah.
26. Trig identities

Whats significance does the identity: sin2x = 2sinxcosx have?
27. Trig identities

HOLY oh man, I am real angry right now. I left my calculator in radian mode and I was using degrees for like the last 40 mins !
28. Trig identities

What happens to the 2x ?
29. Simple probem check

Homework Statement Sin ^{4}X - cos^{4}X Homework Equations The Attempt at a Solution I'm just checking if I can switch the sin and cos at the beginning to make: -Cos^{4}X + Sin^{4}X Then multiply by -1 to basically switch the the Sin and Cos around? I'm supposed to...
30. Trig identities

I'm still stuck. I used the inverse sin of the (root3)/2 and I got answers like pi/3, 2pi/3, ect. I think I need to use the identity but it seems impossible to figure out: 2sinx cosx = (root3)/2