# Posts by DanH

Total # Posts: 100

**Phyiscs**

The child is going from a speed of 112 mi/h to a speed of 0 in .12 seconds...so their is a deceleration...Does this help?

*November 25, 2009*

**Algebra**

If you have to factor this, start with: (w )(w ) Then you need two factors that when ADDED together gives you -11, and when multiplied together gives you 30. Can you come up with these factors?

*June 2, 2009*

**Algebra ll**

subtract 3t^2 - 1 from both sides, and you get 4t^2 - 4t + 1 = 0. Then factor. Can you do that?

*March 24, 2009*

**math**

no, it is not. The ordered pair (1,19) does not satisfy the first equation, because y must be less than or equal to 7x-13. If x = 1, then y cannot be 19.

*March 24, 2009*

**Math**

The y-intercept is where it crosses the x-axis (where x = 0). So, just set x to be 0 and solve for y, and that gives you your y intercept. the same is true for the x-intercept (where y = 0)

*March 2, 2009*

**Chemistry**

This is "zinc 67"

*February 23, 2009*

**math**

It's hard to tell the way you wrote it...it looks like x raised to the 2 power times y raised to the 6 power...then there's a -3 in there...where does the -3 come in? is that an exponent?

*February 18, 2009*

**math**

When you have en exponent...in this case x is raisid to the -3 power, and that is raised to another power, you MULTIPLY the exponents...so, this would be x raised to the -6 power.

*February 18, 2009*

**8th math(Algebra)**

If you subtract the second equation from the first, the a's cancel out. then you get 4b = -2. Can you do the rest?

*February 18, 2009*

**Alg 2**

Pull a 2 out first... 2(a^2 - 8ab + 32b^2) That should get you started

*January 7, 2009*

**math help me plz**

You should be ADDING the 2 equations...so it should be 12x = 132, instead of 2x = 132

*January 7, 2009*

**algebra word problem**

Divide the mass of the sun by the mass of saturn. (1.998 x 10^27)/(5.688 x 10^23). What do you get when you do this on your calculator?

*December 4, 2008*

**physics!-concervation of energy equations**

So, it depends on what you're currently studying. If you're studying equations of motion, then use my first suggestion, but if you're studying conservation of energy, use mgh = (1/2)m*v^2. The m's cancel out: So, gh = v^2/2. You can solve for v, the velocity, ...

*December 4, 2008*

**physics!-concervation of energy equations**

wait...if this is conservation of energy, better to use: convert the potential energy into kinetic energy! (sorry). potential energy is mgh, and kinetic enery is (1/2)m*v^2

*December 4, 2008*

**physics!-concervation of energy equations**

yes, if the initial velocity is squred

*December 4, 2008*

**physics!-concervation of energy equations**

you can use: (vf)^2 = (v0)^ + 2as where vf is "final velocity" v0 is "initial velocity" a is acceleration and s is distance

*December 4, 2008*

**MATH**

Try to specific and tell us what exactly you do not understand

*December 4, 2008*

**MATH**

Use interest = principle x rate x time. I'm not sure what you mean by "base." Principle here is $500, rate is 1.5%, and interest is $3.75. Can you solve it from here?

*December 4, 2008*

**Chemistry ? please**

e- simpley stands for electron, and e-s for electrons (plural)

*December 4, 2008*

**math**

you're welcome!

*December 4, 2008*

**math**

y = mx + b, and you're right, we do not know the y-intercept here. so, y = (2/5)x + b. They tell us the X-intercept is 4.5. How does this help us? The x-intercept is where it crosses the x-axis. At that point, y = 0. So, the line crosses the point (4.5,0). So, now we ...

*December 4, 2008*

**physical science**

Avogadro's number is the number particles of substance in one mole of that subtance. Or, to state it the oppsosite way: One mole of a substance contains Avogadro's constant number of particles of that substance.

*December 4, 2008*

**math**

Start with the equation of circumference of a circle: c = pi x d. The diamter is 2 x radius. So, the diameter of the first cirlce is 18cm. You know the diameter of the second circle. So, how do the circumferences compare?

*November 26, 2008*

**Organic Chemistry**

Woops, sorry Marissa for the delay; just saw your question! Remember, Sn1 reactions are based on the stability of the carbocations formed in the intermediate step. And Sn2 is favored if the carbocation formed is very unstable, thus it occurs in 1 step, without the intermediate...

*November 26, 2008*

**Chemistry!!**

The way you have it written the oxygens do not balance. It is actually: 4Fe + 3O2 > 2Fe2O3. (or, 2Fe + 1.5O2 > Fe2O3. So, basically 2 moles of Fe goes to form one mole of Fe2O3. Then, you must calculate how many moles of Fe you start with, and then you know how many ...

*November 22, 2008*

**Chemistry!!**

Yes, you need the equation. The one you wrote is a start, but you need to BALAMCE it. Do you know how to do that?

*November 22, 2008*

**health**

you are correct. Genetics plays a strong role in alcoholism

*November 19, 2008*

**health**

You are correct...it is all the above...promiscuity and early sexually active behavior are risk factors for cervical cancer

*November 19, 2008*

**Math Check**

you're welcome!

*November 19, 2008*

**Math Check**

yes, that is right..2x + 2y = 112. And, yes the first equation for #4 is x + y = 110. For the second equation...remember, it is 10 years ago...we have to take 10 off each of their ages...(x-10) - (y-10) = 10. Do you understand? 9

*November 19, 2008*

**Math Check**

The first is correct. 2. Should be 4x + (y/4) = 42 3x - (y/2) = 26 3 and 4 are also incorrect. For #3, they tell us that 5 times the length eauals 12 times the width. that translates to 5x = 12y. Can you get the second equation? (remember the perimeter is 2 x length + 2 x ...

*November 19, 2008*

**Algebra 2**

You're welcome

*November 3, 2008*

**Algebra 2**

sqrt(b^2 - 4ac). b is -1 and a is 1 and c is 2. So, sqrt(b^2 - 4ac) is sqrt(-7), or (sqrt7)i.

*November 3, 2008*

**Algebra 2**

No, that is not the answer I get when I plug in to the quadratic formula. I get (1 + sqrt7i)/2 and (1 - sqrt7i)/2 Do you understand how I got this?

*November 3, 2008*

**math**

how about 3 and -2? So you have (x+3)(x-2) = 0

*November 3, 2008*

**math**

OK. x^2 + x - 6: Start with (x )(x ) We have to figure out 2 numbers when MULTIPLIED by each other gives -6, and when ADDED together gives 1. can you figure out these?

*November 3, 2008*

**math**

correct.

*November 3, 2008*

**math**

Start by factoring the equation. Do you know how to do that?

*November 3, 2008*

**math**

The slope-intercept form is y = mx + b, where "m" is the slope, and "b" is the y-intercept. So, here the slope 7/10, and the y-intercept is -10/7

*November 2, 2008*

**physics**

The time it takes to get across is 240m divided by 3.8 m/s, which is 63.2 seconds. In that time the current has moved boat downstream by: 1.6 m times 63.2 seconds, or 101.1 meters. Then to get the resultant velocity, you need to add the velocity vectors. Use pythagorean ...

*November 2, 2008*

**math!**

yes. Now, you need the second derivative, which in this cae is 6x. So, at the first "critical point,-1.4, the second derivative is negative, so at that point, so it is a maximum. At the second point 1.4, the second derivative is positive, so the graph is a relative ...

*October 23, 2008*

**college calculus**

Here's how you get 31: You are correct that a = -12. Do, now the function becomes: f(x) = x^2 - 12x + b. Now, we know that x is 6 and y is -5. So plug these in: -5 = 6^2 - 12(6) + b solve for b and get 31. Do you understand?

*October 23, 2008*

**BIO**

Yes, absolutely right!!!

*October 22, 2008*

**BIO**

If the traits are on the y-chromosome, and are DOMINANT...that means that ALL the offspring BOYS will have the trait, but NONE of the offspring GIRLS will have the trait. Do you see why?

*October 22, 2008*

**Math**

multiply the top equation by 2...it becomes: 6a - 2b = 18. Then you can add the 2 equations together. The b's cancel out. you get 8a = 32. a = 4.

*October 15, 2008*

**Physics**

False. The energy of a wave is proportional to the square of the amplitude. So, doubling the amplitude increases the energy four-fold

*May 6, 2008*

**Algebra Problem**

you are correct

*March 21, 2008*

**Health care please check my answer**

You are correct!

*March 19, 2008*

**English - Criticla thinking**

The answer should be D...the author sites an opinion of an "expert."

*March 19, 2008*

**physics**

The work done by the spring is the elastic potential energy, which is (kx^2)/2. The energy dissipated by the friction is the work done by the friction force (the friction force x the distance). These two things added together (the work of the spring and the energy of the ...

*February 28, 2008*

**physics again...**

you're welcome!

*February 28, 2008*

**physics again...**

OK, you can do it that way. First, he has potential energy = mgh. This gets converted into kinetic energy. The kinetic energy when he hits the water is (mv^2)/2, so you can calculate his velocity when he hits the water. Then calculate his deceleration, and the force.

*February 28, 2008*

**physics again...**

yes, in my first equation, the "s" is distance, or in this case, height.

*February 28, 2008*

**physics again...**

First, calculate the velocity when he hits the water using: V(f)^2 = V(o)^2 + 2as Then, calculate the deceleration as he goes through the water using: V(f) = V(o) + at. Then you can get the force once you know a with F = ma.

*February 28, 2008*

**math**

The x intercepts are where the equation Y is equal to 0. So, just set up equation: 0 = x^2 + 2x - 8. can you take it from here??

*February 28, 2008*

**Science**

Since you have to ADD energy to the reactants in an endothermic reaction, the energy is on the left side: something + energy = something

*February 28, 2008*

**Physics**

KE at base of hill gets converted into potential energy at the top, plus remaining kinetic energy of bicycle moving. Thus, KE(base) = PE(top) + KE(top). (mv^2)/2 base = mgh + (mv^2)/2 top. Note the masses cancel out. v^2/2(base) = gh + v^2/2(top) 400/2 = (9.8)(4.4) + v^2/2(top...

*February 25, 2008*

**math**

2) A is correct 4): I think the point of this question is that the teacher wants a RANDOM sample of students. The only choice that would really give her a random sample would be C. All others are biased.

*February 9, 2008*

**Chemistry**

Your answer sounds excellent to me.

*February 9, 2008*

**Chemistry**

yes.

*February 9, 2008*

**Chemistry**

I think you are close. You will find that the distinction between organic and inorganic is often somewhat nebulous. Yes, in general, organic compounds contain carbon and inorganic do not...but not always!! for example, carbon dioxide, sodium cyanide, and sodium bicarbonate are...

*February 9, 2008*

**chemistry**

yes, I agree: both ethanol and isopropanol have LOWER boiling points than water.

*February 9, 2008*

**chemistry**

Choice A is incorrect.

*February 9, 2008*

**microbiology**

The violet color will wash away with water. The reason for adding the iodine is that it chemically binds to the crystal violet, and makes a water-insoluble complex.

*February 8, 2008*

**algebra**

you need to factor out an x out of each, so the answer actuall is: x(x-6)

*February 7, 2008*

**algebra**

correct

*February 7, 2008*

**algebra**

I'd pick the last second one you wrote.

*February 7, 2008*

**Physical Science**

The answer you have is correct, but it is the CHANGE in length, not the new length. So, the new length is the old length (1.2m) + the answer you came up with.

*February 7, 2008*

**algebra**

6^3 is perfectly correct.

*February 7, 2008*

**Chemistry**

Ba is ++, and NO3 is -. So, it's Ba(NO3)2

*February 7, 2008*

**Physical Science**

That is correct, although you may want to keep it to 2 significant figures, since the first volume is 2 sig figs: Vf = 0.32 cubic meters.

*February 7, 2008*

**algebra**

I'm sorry. I really don't know what they mean by "variable substitution!"

*February 7, 2008*

**algebra**

yup, simple as that!!

*February 7, 2008*

**algebra**

yes.... you have x^2 - 6 = 0, so, x = + and - sqrt6 AND x^2 - 3 = 0, so, x also = + and - sqrt3

*February 7, 2008*

**algebra**

yes!! so you have it factored. Then to get the "roots," set each one equal to 0.

*February 7, 2008*

**algebra**

you need, of course, to factor this. Start by doing this: (x^2 - )(x^2 - ) =0 Can you fill in the blanks?

*February 7, 2008*

**algebra**

(7-2x^4)(7-2x^4) first, multiply the first two: 7x7=49 then, multiply the outside two:7 x -2x^4, which is -14x^4. then, multiply the inside two, which is also -14x^4 then, multiply the last two: (-2x^4) x (-2x^4) which is 4x^8. so, we have: 49 -14x^4 -14x^4 + 4x^8. simplified ...

*February 7, 2008*

**algebra**

woops. this one, if I'm seeing it right... you would have (7-2x^4)(7-2x^4), and then you have to use the "FOIL" method...right?

*February 7, 2008*

**algebra**

you got it!!

*February 7, 2008*

**algebra**

correct

*February 7, 2008*

**algebra**

the answer is 8x^2 - 13x - 14...but there is no denominator. If I understood it right, initially there is 1/2 in the denominator. To get rid of it, you mulitiply it by 2/1, and it cancels out. then you also multiply the numerator by 2/1, to get the answer you got!

*February 7, 2008*

**story problem**

no problem. you're doing very well!!

*February 7, 2008*

**story problem**

correct

*February 7, 2008*

**algebra**

correct!

*February 7, 2008*

**algebra**

you're right!!

*February 7, 2008*

**algebra**

this is right.

*February 7, 2008*

**algebra I**

Oh...ok, of course... 2^-n is the same as (1/2)^n.

*February 7, 2008*

**algebra I**

I am sorry, but the second part of the problem "express your answer to the question as power of 2" is confusing to me. Certainly, if you flip the coin TWICE, then it's a power of 2, as you said, but if you flip it N times, I don't know you can express this as...

*February 7, 2008*

**algebra I**

It is right!!

*February 7, 2008*

**algebra**

now cancel your x+1 and you got it... actually I got over 1/(x-4)(3x-2)...slightly different.

*February 7, 2008*

**algebra**

you are right!

*February 7, 2008*

**literacy/plurals**

Do you know what the plural of leaf or knife is?

*February 5, 2008*

**algebra 2**

see below

*January 29, 2008*

**algebra2**

woops...slight mistake. It's actually: (9+sqrt33)/8 and (9-sqrt33)/8 or 14.74/8 and 3.26/8.

*January 29, 2008*

**algebra2**

ok. I assume you know the quadratic formula. It is hard to write it here. In your example, a = -4, b = -9 and c = -3. So, when you plug these in, you end up with (9+sqrt43)/8 and (9-sqrt43)/8 this is approx: 15.56/8 and 2.44/8. These are your 2 solutions.

*January 29, 2008*

**algebra2**

This looks like a "prime" quadratic. With trial and error trying: (-4t )(t ) or (-2t )(t ) you cannot get it to work. So there are no "interger" solutions. You can use the famous "quadratic equation" to get an approximation. ARe you familiar with ...

*January 29, 2008*

**algebra**

You need to translate the information they give you to algebraic equations. Remember, an isosceles triangle has 2 sides equal to eachother and one not. So, if you call x the length of the sides that are equal, and y the length of the base, then you can make the first equation...

*January 29, 2008*

**Algebra II**

There's a rule for factoring this type of polynomial: x^3 - a^3 = (x-a)(x^2 + ax + a^2) Can you take it from here??

*January 29, 2008*

**To regular teachers**

In trying to help Margie with algebra, it required intensive, step-by-step process. It would certainly be alot more efficient if there were a way to provide instant messaging in a situation like this. Is there a way via your site to communicate with instant message with the ...

*October 14, 2006*

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