# Search results

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. ### 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...
3. ### 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...
4. ### 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...
5. ### 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?
6. ### 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...
7. ### 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...
8. ### 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?
9. ### 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?
10. ### 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...
11. ### Trig identities

Homework Statement 2sin(2x) - \sqrt{3} = 0 Find the value of the variable. Homework Equations Sin(2x) = 2SinxCosx The Attempt at a Solution I subtracted root3 and then divided everything by 2 which leaves me with sin (2x) = \sqrt{3}/2 then I used the double angle identity to change...
12. ### More SAT math questions.

Homework Statement (n/(n-1)) x (1/n) x (n/(n+1)) = 5/k for positive integers n and k, what is the value of k> Homework Equations The Attempt at a Solution I multiplied the left side out to be (n/(n^2-1) and set it equal to 5/k I got stuck right there.
13. ### SAT MATH QUESTIOn

Homework Statement In a Mixture of peanuts and cashews, the ratio by weight of peanuts to cashews is 5 to 2. how many pounds of cashews will there be in 4 pounds of this mixture? Homework Equations The Attempt at a Solution I used 5/2 as seven pounds in the original ratio...
14. ### Explain the concept of significant figures?

Homework Statement How many significant figures in each?: -214 -81.60 -7.03 -.03 -0.0086 -3236 -8700 I don't quite understand this (I'm self studying, need a little help :) ) If got them all right then can someone explain the concept of significant figures? I hate knowing only...
15. ### Derivations of dimensions problem

Homework Statement Dimensions: These derivations are not correct ( as stated by the book) I'm just reading my textbook at the moment and I saw this example ( So I don't have work for it myself by the book shows all the steps). ***√[L]/[L/T^2] =√[T^2] Homework Equations The...
16. ### Stupid measurement question

Homework Statement Would 85 uV (Micro) be 8.5 x 10^-5 V ? And would 600ps be 6x 10^-10 S ? Ehhh I havent slept in weeks, I just can't focus. Homework Statement Homework Equations The Attempt at a Solution I used the fact that 1u = 1x 10 ^-6 and then I used 1V/1000000uV x (85 uV)...