dcowboys107

(1-x^2)^(1/2)

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

One minus x squared divided by 4 minus x squared all under a square root sign.

My teacher says the domain is (-inf,-2) union [-1,1] union (2,inf)

Is it necessary to include the [-1,1]?

Wouldn't it be obvious that function is valid at that point?

I have a tough time deciding when to include those terms

How do I know when to include the infinity and such?

You have it right. Thans for the info!

[math]\frac{0}{0}[/math] is an indeterminate form, which allows you to L'Hopital. So I would suggest you try and apply L'Hopital to these.

I don't think we used L'Hopital or something. Is their a different way?

I have some limit problems and I'm not sure how to do it. I already have the answers so I'm not asking for answers but the "how to".

lim (1/x)-(1/3)

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x--->3 (x-3)

lim (t+4)^(1/2)-2

t-->0 -----------

t

I always end up getting 0/0 on all the fractions. I'm not sure what to do for these. Thanks!

I think I got it to work. Does that seem like the right answer though?

Write equations for the two straight lines that pass through the poing (2,5) and are tangent to the parabola y=4x-x^2.

I drew the figure and the lines. I fought the slope for the tangent lines (2 and -2) and eventually the equations y=-2x+9 and y=2x+1

When I plugged the three equations into my calcuator to see if I was right it seems that I was off on y=-2x+9, that it doesn't reach 5 when x is two but at 4. The second one seems right.

Am I right and the calcultar be wrong? Thanks.

From a point on level ground, an observer measures the angle of elevation to the top of a hill to be 38 degrees The observer then walks 370 meters directly away from the hill and measures the angle of elevation to the top of the hill to be 25 degrees. Determine the height of the hill to the nearest meter.

I drew it out and for variables I used "x" as the distance from the first angle measurement to the base of the hill and 370 from the end of the first measurement to the start of the second measurement. I used "h" to represent height. I got cot 38 degrees=x/h and cot 25=(370+x)/h I solved for x in the first equation then plugged it into the second and got finally h=370/(cot 25 - cot 35) why is this answer wrong? Thanks for the help!

Rewrite f(x) = 4csc^2(x) + 9tan^2(x) in terms of cos(x).

NOTE: Expressions such as cos^2(x) must be entered as cos(x)^2 or (cos(x))2.

I rewrote csc(x)^2 as 1/1-cos(x)^2 and tan^2 as ((1-cos(x)/cos(x))^2

I'm having a hard time simplifying that down to just cos(x).

What is the value of x for these equations?

a. Find all solutions for this equation:

(e^2x)-(6e^x)+32/4=0

b.(e^x)-24e^(-x)=-2

Use common logs to solve for x in terms of y for the following:

c.y=10^x+10^(-x)

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18

I don't know even where to start. . . I'd apprecite all the help possible.

I'm still not getting the answer. . . could you show me step by step?

a.ln(x)-ln(6-x)=3

b.log base 2 of (x+5)=log base 2 of (x-5)+log base 6 of (36)+6^(log base 6 of 3)

a.ln(x) - ln(6-x) = 3

ln(x/(6-x)) = 3

x/(6-x) = e³

I've gotten this far for part a but now I can't solve for x.

log[base 2] ((x+5)/(x-5)) = 2 + 3

(x+5)/(x-5) = 2^5

Part b I've gotten this far. It says not to give a decimal approximation for any of the problems rather a fraction or an exact expression. Can someone show me how to solve for x in these two problems? Thanks!

I got -3/10 by using -b/2a. I put it into the expression and got said number.

How do you find the what the value is then?

The graph of a quadratic function f(x) has its vertex at (5,-6) and passes through the point (2,-51). Find a formula for f(x)

I got 15(x-5)^2 - 6 Why is this wrong?

Find the minimum value of the function

(5x-2)(2x+2). I got -49/20 after multiplying out the equation to get

5x^2+3x-2 (simplified). I did -3/10 and put it back into the equation and got it wrong. . .

Any ideas?

We have to enter our answers online and it says I've gotten the wrong answer. . . How do I enter the answer in? I'm very confused becuase I feel like I've done it right. . .

It has been estimated that 1000 curies of a radioactive substance introduced at a point on the surface of the open sea would spread over an area of 20,000 km2 in 20 days. Assuming that the area covered by the radioactive substance is a linear function of time t and is always circular in shape, express the radius r of the contamination as a function of t.

Apparently Area = constant * t.

As 20,000 km2 = constant * 20 days, the constant equals 1,000 km2/day

Therefore Area = 1,000 km^2/day * t

On the other hand Area = pi r^2.

So pi r^2 = 1,000 km^2/day * t, meaning that

radius r = sqrt (1000/pi km^2/day) * t^(1/2)

I got this far but I don't think the answer has km as part of the solution. I'm sure that there is a pi involved. Any ideas?

The Solubility of barium hydroxide in water at 20 degrees C is 1.85g/100g Water. A solution is made up of 256 mg in 35.0 g of water. Is the solution saturated? If not, how much more needs to be added to make a saturated solution?

This is what I have done so far: ?g of Ba(OH2)2=35.0g water x (1.85 g/100g)=.6475 g is needed to form a saturated solution. .6475-.256= .392g is needed to make is saturated.

Is this right? Some of my classmates got conflicting answers. Thanks for the help!

What would the electron configuration (complete or abbr. which ever is easier to make the point) of Ga+3, Fe+2 and +3, and Zn+2? Why does zinc not just lose one electron and have a half full shell? I'd appreciate any explanation on how to predict ionization!

I have just recieved my grade on my enthalpy test (78) and have a few questions in which my teacher was unable to answer to my understanding.

1. In exothermic reactions, the products contain more heat than do the reactans. Sometimes True, Never True, or Always True? I put AT because wouldn't the products gain heat from the reactant?

2. Here is a multiple choice question in which I also missed: A limiting Reactant: a. may be heat but only in an exothermic reaction.

b. may be heat but only in an endothermic reaction

c. does not involve the heat change at all

d. both a and b are correct

e. none of the above.

The answer for 2 is "B" but why?

what would the descriptive symbol for trinitrobenzene be? I'm assuming it's liquid based on the problem. Could it be aqueous? thanks!

Benzene (C6H6) reacts with nitric acid. Two products are produced, one of which is water. The other product is an oily liquid which has molar mass of 213 g/mol. It contains 33.8% Carbon, 1.42% Hydrogen, 19.7% Nitrogen, and 45.08% Oxygen. Write a balanced equation complete with descriptive symbols for this reaction.

I converted each to moles so for carbon I got 2.816, Hydrogen 1.42, and Nitrogen, 1.407 and oxygen 2.8175. Then I divided by the smalles and expressed to a whole number ratio. So for each one respectively: Carbon 2, Hydrogen 1, Nitrogen 1 and Oxygen 2. So the supposed emperical forumula should be C2HNO2. The molar mass for the molecular formula is 213 g/mol I divided the molar mass of the empirical formula and divided into 213 and got 3.

My final answer turned out to be C6H3(NO2)3. I feel suspicous that this is incorrect. My equation is this: C6H6(l) + HNO3(Aq) ----> H2O(l) + C6H3(NO2)3.

What did I do wrong? please show me and if you wouldn't mind checking to see if my symbols are right, etc. Thanks!

2 + 1 + 3 + 2 = 8

The number 21328 has a unique feature: The sum of the first four digits equals the units digit. How many EVEN five-digit numbers have this unique property?

I have the file right here. Thanks for your help! I'd appreciate an explanation on how you solve the problems.

A

28

496

8128

33550336

8589869056

137438691328

Determine the value of A that begins this pyramid of numbers and also provide your reasoning for determining this value.

Jack Handley's new telephone number, together with the area code, forms a ten-digit number consisting of a pair of 1's separated by one digit, a pair of 2's separated by two digits, a pair of 3's and a pair of 4's both separated by three digits, and a pair of 5's separated by five digits. Neither the sixth nor the ninth digit is a 4.

What is his new telephone number?

What is the smallest number that is divisible by 13 but when divided by the whole numbers 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, and 12 yields a remainder of 1?