Thursday

September 18, 2014

September 18, 2014

Total # Posts: 52

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*April 27, 2013*

**Calc,**

Oops, I should have been more specific. I need to solve it using sums, not antiderivates.
*April 4, 2011*

**Calc,**

Find the value of the definite integral: int= integral sign int((x + 2)/(x^(3/2)),x= 16..25)dx I have no idea how to start this... would I get rid of the fraction?
*April 4, 2011*

**Calculus**

A 24 foot ladder is leaning against a building. Let x be the distance between the bottom of the ladder and the building and let theta be the angle between the ladder and the ground. a)Express theta as a function of x. cos theta = x/24 theta = arccos(x/24) correct/incorrect? b)...
*March 23, 2011*

**Calculus**

Could someone please explain this to me? Differentiate. h(u)= 10^(sqrt(u)) h'(u)= 10^(sqrt(u))*log(10)(d/du(sqrt(u))) h'(u)= 10^(sqrt(u))*((1)/(2*sqrt(u)))*log(10)
*March 9, 2011*

**Calculus**

So I get this: = ln Isin(u)I + C = ln Isin(ln x)I + C = ln (sin(ln x)) + C OR = ln (sin(1/x)) + C Is it correct or incorrect?
*March 8, 2011*

**Calculus**

Why is it S (ln u) du = ? What about the sin? And to multiply them are you reciprocating?
*March 8, 2011*

**Calculus**

Evaluate the integral. S= integral sign I= absolute value S ((cos x)/(2 + sin x))dx Not sure if I'm doing this right: u= 2 + sin x du= 0 + cos x dx = S du/u = ln IuI + C = ln I 2 + sin x I + C = ln (2 + sin x) + C Another problem: S ((sin (ln x))/(x)) dx I don't even ...
*March 8, 2011*

**Calc.**

Evaluate the indefinite integral. Please check my work? Not sure if I am doing this correctly. S= integral symbol S x^3*sqrt(x^2 + 1) dx u = x^2+1 x^2= u - 1 du = 2xdx du/2 = xdx 1/2 S x^2 * x sqrt (x^2 + 1) du 1/2 S (u - 1) * sqrt (u) du multiply square root of u and (u - 1) ...
*January 27, 2011*

**Calc.**

But the x is the only thing being squared I thought because it is within parentheses and then multiplied by xcos dx?
*January 27, 2011*

**Calc.**

S is supposed to be the integral symbol and b is the upper bound and a is the lower bound. Yes, xcos(x^2) dx is it.
*January 27, 2011*

**Calc.**

Evaluate the definite integral. S b= sqrt(Pi) a= 0 xcos(x^2)dx I'm not sure if this is right? u= x^2 du= 2xdx du/2= xdx S (1/2)cos(u) S (1/2)*sin(x^2) [0.5 * sin(sqrt(Pi))^2] - [0.5 * sin(0)^2] 0 - 0 = 0, so zero is the answer?
*January 27, 2011*

**Calc.**

a)If f(x)= x/(x+2), 1 less than or equal to x less than or equal to 4, find the left and right sums for n= 10, 30, and 50. b)Illustrate by graphing the rectangles in part a. c)Show that the exact area under f lies between 1.603 and 1.624. So this is all I know and I'm not ...
*January 13, 2011*

**Calc**

If f(x)= sec x, find f"(Pi/4) I am not sure how to take the 2nd derivative? f'(x)= sec x tan x f"(x)=??? Is it f"(x)= (sec x tan x)(sec^2x)??? Please Help!
*October 24, 2010*

**Calculus**

How else would you go about it?
*October 24, 2010*

**Calculus**

Differentiate. y= u(a cos u + b cot u) I am not sure if this correct. I was not sure whether to leave the variables as are or where the negatives should be placed? (u)*(- a sin u - b csc^2 u) + (a cos u + b cot u)*(1)
*October 24, 2010*

**calculus**

Find the points on the curve y= (cos x)/(2 + sin x) at which the tangent is horizontal. I am not sure, but would I find the derivative first: y'= [(2 + sin x)(-sin x) - (cos x)(cos x)]/(2 + sin x)^2 But then I don't know what to do or if that is even correct??? Would I...
*October 24, 2010*

**Calculus**

Ok, so here is what I think. a) f(1)=2 g(1)=x+2 1+2= 3? b)lim x->1+ f(x)=0 lim x->1+ g(x)= 2? c)g(0)=2 f(2)= ???? d) lim x->0- g(x)=0 lim x->0- f(x)= 1? Right or Wrong?
*October 13, 2010*

**Calculus**

Posted by CMM on Wednesday, October 13, 2010 at 12:50am. Calculate the following: a) Find g(f(1)) b) Find lim x-> 1+ g(f(x)) c) Find f(g(0)) d) Find lim x->0- f(g(x)) f(x)= 1-x, x<1 1, x=1 x-1, x>1 g(x)= -x, x<0 2, x=0 x+2, x>0 This is where it gets hard. I ...
*October 13, 2010*

**Calc. Repost- Please Help**

I'm just as confused!
*October 13, 2010*

**Calc. Repost- Please Help**

Calculate the following: a) Find g(f(1)) b) Find lim x-> 1+ g(f(x)) c) Find f(g(0)) d) Find lim x->0- f(g(x)) f(x)= 1-x, x<1 1, x=1 x-1, x>1 g(x)= -x, x<0 2, x=0 x+2, x>0 This is where it gets hard. I have a graph for f(x) and one for g(x). I will explain ...
*October 13, 2010*

**Calc.**

Calculate the following: a) Find g(f(1)) b) Find lim x-> 1+ g(f(x)) c) Find f(g(0)) d) Find lim x->0- f(g(x)) f(x)= 1-x, x<1 1, x=1 x-1, x>1 g(x)= -x, x<0 2, x=0 x+2, x>0 This is where it gets hard. I have a graph for f(x) and one for g(x). I will explain ...
*October 12, 2010*

**Calc- Urgent Please**

An open box (has a bottom but no top) needs to be constructed which has a volume of 500 cu. in. The bottom of the box is to be a square. Let x be one of the sides of the bottom. Express the area of the four sides and bottom of box as a function of x alone. What value of x will...
*October 12, 2010*

**Calc**

Find f'(a). f(x)= (x^2 + 1)/(x - 2) So, [[(a + h)^2 + 1]/[(a + h) - 2]] - [(a^2 + 1)/a - 2] and the whole thing divided by h I tried simplifying it and ended up with [a + h/-2] - (a-2), which is incorrect. I used wolfram alpha and got (a^2 - 4a - 1)/(a - 2)^2 but I do not ...
*September 28, 2010*

**Calculus**

Find f'(a). f(x)= (x^2 + 1)/(x - 2) So, [[(a + h)^2 + 1]/[(a + h) - 2]] - [(a^2 + 1)/a - 2] and the whole thing divided by h I tried simplifying it and ended up with [a + h/-2] - (a-2), which is incorrect. I used wolfram alpha and got (a^2 - 4a - 1)/(a - 2)^2 but I do not ...
*September 28, 2010*

**Calc**

Use a table of values to estimate the value of the limit. lim (tan 3x/tan 5x) x--> 0 I have no clue what to do. Could someone please explain how to go about this problem.
*September 26, 2010*

**Calculus**

If a rock is thrown upward on the planet Mars with a velocity of 10 m/s, its height in meters t seconds later is given by y = 10t - 1.86t^2 a) Find the average velocity over the given time in intervals: (i) [1,2] (ii) [1,1.5] (iii) [1,1.1] (iv) [1,1.01] (v) [1,1.001] Do I just...
*September 25, 2010*

**Org. Chem.**

1. Find examples of reagents used in performing chemical resolutions of acidic, basic, and neutral racemic compounds. 2. Propose methods of resolving each of the following racemic compounds: A) CH3CH(Br)C=OOH B) Don't know how to name, but it's a benzene ring with ...
*March 1, 2010*

**Org. Chem.**

1. Find examples of reagents used in performing chemical resolutions of acidic, basic, and neutral racemic compounds. 2. Propose methods of resolving each of the following racemic compounds: A) CH3CH(Br)C=OOH B) Don't know how to name, but it's a benzene ring with ...
*February 27, 2010*

**Org. Chem.**

Draw a mechanism that explains how the nitro-substituted aromatic products observed in your reaction were formed. My sample was nitrodiphenylmethane and three peaks were observed using GC/MS. I wasn't sure how to determine what the peaks meant exactly. We had to use SDBS ...
*February 18, 2010*

**Org. Chem.**

Synthesize 6-(4-tert-butylphenyl)cyclohex-3-enecarbonitrile using (Z)-3-phenylacrylonitrile as your starting material and any other reagents you wish. Please help and an explanation would be greatly appreciated.
*February 8, 2010*

**Org. Chem.**

Oops, I didn't get the correction note before I submitted, but thanks I appreciate your help.
*January 27, 2010*

**Org. Chem.**

Thank you so much. However, I thought B) hexanoic acid had to have a C=OOH?
*January 27, 2010*

**Org. Chem.**

Provide methods for preparing the following compounds by the Grignard method: A) 3-pentanol B) Hexanoic acid There are also 2 more, but I don't even know how to name them. C) CH3CH2CCH3OHCH2CH3 D) A cycloalkene (3 double bonds-alternated) with CHOHCH2CH3 attached to it ...
*January 27, 2010*

**Chemistry-please help!**

When sucrose is fermented to produce ethanol why is it not possible to obtain a final solution containing more than 10-15% ethanol? Does this have to do with azeotropes? However, I thought this was possible? I am confused, please help.
*December 8, 2009*

**Chemistry-please help!**

When sucrose is fermented to produce ethanol why is it not possible to obtain a final solution containing more than 10-15% ethanol? Does this have to do with azeotropes? However, I thought this was possible? I am confused, please help.
*December 8, 2009*

**org. chem.**

When sucrose is fermented to produce ethanol why is it not possible to obtain a final solution containing more than 10-15% ethanol? Does this have to do with azeotropes? However, I thought this was possible? I am confused, please help.
*December 7, 2009*

**org. chem.**

Why is it not possible to achieve a complete separation of the ethanol from the water in the clarified reaction mixture via simple distillation? I'm not sure about this because I thought the difference between fractional (what was done) and simple distillation is that ...
*December 7, 2009*

**Org. Chem.**

Why is it not possible to achieve a complete separation of the ethanol from the water in the clarified reaction mixture via simple distillation? I'm not sure about this because I thought the difference between fractional (what was done) and simple distillation is that ...
*December 7, 2009*

**Org. Chem.**

When sucrose is fermented to produce ethanol why is it not possible to obtain a final solution containing more than 10-15% ethanol? Does this have to do with azeotropes? However, I thought this was possible? I am confused, please help.
*December 7, 2009*

**Org. Chem.**

I believe the 1-butene forms by an SN1 mechanism and the dibutyl ether forms by E1 mechanism, but I am still not sure which are the nucleophiles, electrophiles, leaving group, etc.?
*December 1, 2009*

**Org. Chem.**

Experiment= synthesis of n-butyl bromide, using n-butyl alcohol, NaBr, H2SO4. A) An ether and an alkene are formed as by-products in this reaction. Draw the structures of these by-products and give mechanisms for their formation. I believe the two products are dibutyl ether ...
*December 1, 2009*

**Org. Chem.**

If n-butyl alcohol, sodium bromide, water, and concentrated sulfuric acid (cooled in ice bath while adding H2SO4) are placed in a flask and refluxed, what are the formulas of the salts that precipitate when the reaction mixture is cooled?
*December 1, 2009*

**Chem. To Dr. Bob from Earlier Question or anyone**

Dr. Bob, earlier you gave me the equation H2SO4 + NaHCO3 -> H2O + CO2 + Na2CO3 to balance. However, the S is not in the products, so it can't be balanced.
*November 30, 2009*

**Density**

If the actual density is 1.2686 g/mL and the determined density by experiment was 1.0275 g/mL, is it reasonable to conclude the obtained product was fairly pure. I am writing a lab report and these were my results and interpretation, but I am not sure if the difference between...
*November 30, 2009*

**Org. Chem.**

We did an experiment on the synthesis of n-butyl bromide using n-butyl alcohol and H2SO4. Why does the alkyl halide layer switch from the top layer to the bottom layer at the point where water is used to extract the organic layer? Please Help.
*November 30, 2009*

**Org. Chem.**

Thanks, but what happened to the S in the equation? There needs to be one in the products to balance.
*November 30, 2009*

**Org. Chem.**

We did an experiment with the synthesis of n-butyl bromide, using n-butyl alcohol, NaBr, and H2SO4. The question is: Aqueous sodium bicarbonate was used to wash the crude n-butyl bromide. A) What was the purpose of this wash? Give Equations. I know it was used to remove any ...
*November 30, 2009*

**Org. Chem.**

A natural product (MW=150) distills with steam at a boiling temperature of 99 degrees Celsius at atmospheric pressure. The vapor pressure of water at 99 degrees Celsius is 733 mm Hg. A) Calculate the weight of the natural product that codistills with each gram of water at 99 ...
*November 10, 2009*

**org. chem.**

Thank you very much.
*November 9, 2009*

**org. chem.**

Explain how caryophyllene fits the isoprene rule. I don't know how to explain this. I do know the isoprene rule is (C5H8)n, where n is the number of isoprene units. Please help.
*November 9, 2009*

**Org. Chem. Please Help**

I solved for o and got 0.306957708 grams. Correct? For B, I did this: 0.5 X 0.10 = 0.05 g 0.306957708 - 0.05 = 0.256957708 g of water, which is my answer. Correct?
*November 9, 2009*

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