Thursday
July 24, 2014

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?

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?

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

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.

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)

Chemistry
This is "zinc 67"

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?

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.

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?

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

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

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?

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, b...

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

physics!-concervation of energy equations
yes, if the initial velocity is squred

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

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

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?

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

math
you're welcome!

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 subst...

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.

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?

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...

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 mole...

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?

health
you are correct. Genetics plays a strong role in alcoholism

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

Math Check
you're welcome!

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

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 widt...

Algebra 2
You're welcome

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.

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?

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

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?

math
correct.

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

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

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 theore...

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 minumu...

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?

BIO
Yes, absolutely right!!!

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?

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.

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

Algebra Problem
you are correct

Health care please check my answer
You are correct!

English - Criticla thinking
The answer should be D...the author sites an opinion of an "expert."

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 frict...

physics again...
you're welcome!

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.

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

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.

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??

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

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...

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.

Chemistry
Your answer sounds excellent to me.

Chemistry
yes.

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...

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

chemistry
Choice A is incorrect.

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.

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

algebra
correct

algebra
I'd pick the last second one you wrote.

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.

algebra
6^3 is perfectly correct.

algebra
yup

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

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.

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

algebra
yup, simple as that!!

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

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

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

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 ...

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?

algebra
you got it!!

algebra
correct

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!

story problem
no problem. you're doing very well!!

story problem
correct

algebra
correct!

algebra
you're right!!

algebra
this is right.

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

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...

algebra I
It is right!!

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

algebra
you are right!

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

algebra 2
see below

algebra2
woops...slight mistake. It's actually: (9+sqrt33)/8 and (9-sqrt33)/8 or 14.74/8 and 3.26/8.

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.

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 ...

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:...

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??

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 st...

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