Monday

April 21, 2014

April 21, 2014

Total # Posts: 62

**Chemistry**

Oh and I don't think this is a Chemistry question.

**Chemistry**

because The second is the duration of 9,192,631,770 periods of the radiation corresponding to the transition between the two hyperfine levels of the ground state of the caesium 133 atom. A day is how long the earth takes to rotate once and that in our time is 24 hours [well, 2...

**math**

I think it was a typo: it should be = 3 - 2(7) -2(-4y) = 3 - 14 + 8y = 8y - 11

**Math/Algebra 2**

2/x + 3/4x = 8/4x + 3/4x = 11/4x

**alegbra**

x^2-15x-36=-72 therefore x^2-15x+36=0 when you solve this you get (x-12)*(x-3)=0 You can find the 2 solutions from that and multiply them. hope that helps

**Algebra 2**

sorry, i made a mistake 8(x) + 5(2x) = 360 8 per truck, 5 per car

**Algebra 2**

here is a hint, if trucks = x then cars = 2x then x + 2x = $360 see if you can get the rest now. just write what they told you in equation for. hope that helps

**math**

multiply the 1st equation by -2 and then add them to get rid of the y's [and hence find the x] once you have the value of x sub it into either of the two equations to find y. then just do x-y Hope that helps

**7th grade**

for the 1st post - to dim for the 2nd post - adequate hope that helps

**Algebra**

vol = l*w*h the question is that l is doubled to give 2l h is doubled to give 2h and w is tripled to give 3h. so the new vol = (2l)*(2h)*(3w) = 12*l*w*h so 'new vol' = 12*old vol Hope that helps

**Algebra**

yes, spot on. Well done

**Geometry**

A protractor maybe? Hope that helps

**Pre-Calculus**

well, from the above equation y = (x^2)/2 to get an equation of a line you need a slope and a point. You have a point and to get the slope we need to get dy/dx and sub in the value for x in the point given [in this example 4] Then sub your point (x1,y1) and the slope (m) into ...

**Algebra.**

almost, the < sign only changes to a > sign when both sides are multiplied by a minus. so the answer is x<1 Hope that helps

**Algebra**

Spot on. well done.

**4th grade**

1 US pint = 32 US tablespoons there is no work involved. It's a conversion. like 1760 yards in a mile or 1000Kg in a tonne

**Math**

I'll correct myself, yes you can I didn't think of the above method by Reiny. I never used that way before :) It's quite useful though. Sorry for my error

**Math**

No, you have to first use y - y1 = m(x - x1) [point slope form] and then rewrite in the form y = mx + c [slope intercept form] When you are given 2 points you have to find the slope first [m = (y2 - y1)/(x2 - x1)] then sub in the slope with either of the points in the equation...

**4th grade**

yes. All animals (and plants too - and stars aswell) are born [one way or another ] and eventually die. Which is the life cycle. hope that helps

**4th grade**

No, the moon orbits the earth and the earth orbits the sun but the moon does not orbit the sun. (rotate is not technically correct for this description of motion) Hope that helps

**Math**

yes it does. With (x1,y1) = (4,0) and m = 1 The equation for a line is y - y1 = m(x - x1) y - 0 = 1(x - 4) y = x - 4 So, yes you are right. Well done!

**Math**

First question: no, the zero can be dropped Second question: yes it can be changed into (y-2) = (4/5)*x and it can be also be re-written as y = (4/5)*x + 2 [slope intercept form] Hope that helps

**Calculus**

well to get a distance between points we use the distance formula but first we need the points themselves. Point 1 is found by subbing t=0 in for t in x(t) and y(t) Point 2 is found by subbing t=11 in for t in x(t) and y(t) I'll do point 1 x(t) = (0)^2 - 14(0) - 4 = -4 y(t...

**physics**

W = mg W = weight (in Newtons) m = mass (in Kg) g = acceleration due to gravity (in m/s^2) Force in also measured in Newtons so they just want W. Oh and g = 9.8 m/s^2 Hope that helps

**college**

You need to post the statements.

**Alegbra**

ok, you have a line x + 4y = 5 to find the slope re-write in the form y = mx + c where m is the slope and c is a constant in the above line m = -1/4. So we want the equation of a line parallel to the above line but goes through the point (7,9). As I said above parallel lines h...

**Alegbra**

Here is a clue for the question: Parallel lines have the same slope. You have 1 line - find its slope. Hope that helps

**math**

Trial and error really for x and y being whole numbers. You have to see, for example, how many 2's [the 2x bit] to take away from 4 [on the RHS] before it's divisible by -3 [from the 3y bit] For example, from -3y = 4 - 2x x = 5 will give -3y = 6 which means y = -2 The ...

**math**

There is a mistake in bobpursley's equations - both should have the same distance of 48. vs = velocity of stream vb = velocity of boat and Distance = Velocity*Time Downstream 48 = (vb + vs)*3 The stream velocity is +ve as the time is shorter downstream - the stream helps S...

**Math**

It's a straight forward pair of simultaneous equations. In this example just add the two equations to cancel out the y and find the x value. Once you have the x value sub it back into one of the equations to find y. Hope that helps

**math**

well, 49+72+108+121 = 350 and 350/35 = 10. That has got to be the oddest question I've ever seen :) Given the answer and have to find the question - odd :) Hope that helps

**math**

Firstly f(x)=(x=4)(x-2) is wrong you have two = signs. I'm assuming it's a + or another -. a) Well, you know f(x), so -f(x) just has a - in front of it. f(-x) means put -x in everywhere you see x b) f(x), -f(x) and f(-x) are all of the form y = ax^2+bx+c which is a par...

**Pre Calc**

Well if, 5! = 5*4*3*2*1 that's the same as 5*4! isn't it? or 5*4*3! ? Do you see now how to do the question? Hope that helps

**Pre Calc**

To me that doesn't seem like a complete question. You have 1 equation with 2 unknowns. You need a minimum of 2 equations to find 2 unknowns. Another way of looking at it is that the above equation is the equation for a circle with center (2,-3) and radius 3. So asking for ...

**Pre Calc**

Well, a geometric sequence is of the form; a, ar, a(r^2), a(r^3), ... , a(r^n) where t(0) = a, t(1) = ar etc. [the sequence 1, 1/2, 1/4, 1/8, 1/16,... is geometric with a = 1 and r = 1/2] Ok, hope that helps!

**Math**

Ok, I'll do the 1st one; first of all 8 - (-2/3) well, minus times minus = plus [e.g. -4*-4 = 16] so that becomes 8 + 2/3 Now we need to do the same with the rest of the equation to get 8 + 2/3 + 7 - 1 2/3 + 5 You how have to sort out 1 2/3 which is 1 and 2/3 which equals ...

**math**

I'd use a venn diagram. Simple, yet effective.

**physics**

I got r = 9.10x10^14 meters. A correction to the question above is ME = 5.98x10^24 Kg not 5.98x1024 Kg Maybe that's where the mistake is? Hope that helps!

**college math**

drwls, you made a slight mistake - you forgot a factor of 2 in the RHS of the equation. If N1 = x and N2 = 2x + 8 then the equation is x(2x+8) = 8 + 2*(2x + 8 + x) Which simplifies to x^2 - x - 12 = 0 which has two integer solutions. Hope that helps!

**Algebra II/ Trig**

I'd guess it's the area is what the question wants so we need only one of the angles. Now, CosA = 0.05 but A is not 152. [For one reason Cosine is -ve in the 2nd quadrant so the angle must in the 1st quadrant [0<A<90] Angle A = 87.1 Degrees So when you have the a...

**MATH**

Area of Trapezoid = h*((a+b)/2) where a and b are the two parallel sides and h is the perpendicular height. If your a and b are 12 and 5.4 and the perpendicular height is 6 then your equation above is correct.

**physics**

Yes. I believe so.

**physics**

yes -0.544 - (-3.40) = -0.544 + 3.40

**physics**

I'm fairly certain it's D i'll explain my reasons again - hope fully better :) Ok, my example is going to be UV radiation from the sun. a. it transfers energy to objects in the path of the electromagnetic waves When you are outside in the sun UV radiation is, for l...

**physics**

Force is C - Electromagnetic The Strong force binds gluons inside protons and neutrons Yes, I think D is right for the mechanical force one. Yes 5.1 I think it's D - All of the above Here is an example a - UV radiation causes sunburn b - UV radiation is used by Solar panel...

**Algebra II**

Area of a triangle = (1/2)bcSinA Or in words, a half times the length of two sides times the Sin of the angle between those two lines. So Area = (0.5)*(20)*(12)*Sin(56) Area = 120*Sin(56) Area = 99.48 And rounded to the nearest 10th [or to one decimal place in other words] Are...

**chemistry**

With Li, Na and K the reactions are exothermic [give out heat] and you would see flames and the metals would move vigorously on top of the water. The reactivity order is Li<Na<K so K is the most reactive. The reaction of an alkali metal with water gives a Hydroxide and H...

**math-calc**

I'm going to guess that the question is asking for the maximum and minimum of the cubic. Simply find f'[x] = 0 and you will find 2 values for x. To find which is the max and min find f''[x]. and put in the two different values you got [say x1 and x2] and if f&#...

**math-calc**

I made a slight error. i dont want f'[0], i want f'[x] = 0 to find x = something. so we get 5e^(2x) + 2e^(2x)(-4+5x) = 0 divide across by e^(2x) we get 5 + 2(-4+5x) = 0 5 - 8 + 10x =0 10x = 3 x = 3/10 Sorry about the mistake in my first post. hope that helps

**math-calc**

Differentiate and put equal to zero. f'[x] = 5e^(2x) + 2e^(2x)(-4+5x) f'[0] = -3 So the x-coordinate is -3 I'd guess that that is what the question wants. Hope that helps

**math-calc**

f(x) = inf when 6x+3 = 0 or when x=-1/2 That is one of the asymptotes which separate the graph. as for increasing and decreasing, well, from -inf going to -1/2 as x increases y decreases and from -1/2 to inf as x increases y decreases also. If you draw it it has the shape of y...

**math-calc**

it's turning points are when [1] x*7 = 0 or x = 0 [2] (x+2)^2 = 0 or x - -2 The graph is increasing when (-12 to -2) and (0 to 10) To work this out find the turning points by finding f'[x]=0 ok hope that helps

**calculus**

f[x] = 9x + 3/x f'[x] = 9 - 3/(x^2) f'[x] = 0 at min/max 9 - 3/(x^2) = 0 multiply across by x^2 to get 9x^2 - 3 = 0 x^2 = 1/3 x = 1/sqrt(3) or x = -1/sqrt(3) which i will call x1 and x2. to find which is the min and which is the max get f''[x] and sub in the tw...

**Science**

Overall it's a mixture. Like table salt is a mixture [NaCl and KCl] it's the components of the mixture that are compounds but not the overall contents. If you put peas and beans in a bowl that's a mixture but peas and beans are made up of lots of different chemical...

**Algebra**

x = number of houses with floor plan 1 y = number of houses with floor plan 2 x(175,000) + y(200,000) = 7,200,000 7,200,000 is the value of the 38 houses made up of a number of plan 1 houses (x) and a number of plan 2 houses (y). Then solve simultaneously to find x and y. Firs...

**It's been more than 24 hours and no answer...**

Well, the y-value doesn't change and the x-value decreases by 5. If, for example, we had the point (7,4) Under the above translation becomes (2,4) Hope that helps

**Maths**

if it's 1/(2x^2) - x + 4 = 0 Multiply across by 2x^2 to get 1 - 2x^3 + 8x^2 = 0 2x^3 - 8x^2 - 1 = 0 Which is a nasty enough cubic with only 1 root. If the question is (1/2)x^2 - x + 4 = 0 use the -b formula which gives 2 complex roots: 1 + sqrt(7)i and 1 - sqrt(7)i. Hope t...

**algebra 2**

you can factor x^2 - 2x - 8 = 0 (x-4)(x+2)=0 therefore the three zeros [or 'roots' as I know them as] are x = 4, -1, -2

**physics**

I think it's A also. Increase Charge = Increase EFS Increase Distance = Decrease EFS

**chemistry**

Ah, I should have the same as the original figure - 2 decimal places. Thanks!

**chemistry**

c = f*l c = speed of light f = frequency l = wavelength c = 3x10^8 m/s [a constant] l = c/f l = 3x10^8/6.67x10^14 l = 4.49775x10^-7 l = 449.8 nm Hope that helps

**chemistry**

1 mol Potassium = 39g [Atomic Mass of K] x mol Potassium = 25g x = 25*1/39 = 0.641 mol Hope that helps.

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