Wednesday
May 4, 2016

# 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

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

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
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

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

Alegbra 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

1. Pages:
2. 1