Recent content by ~angel~

Thanks for your help, but I can't get the answer. The table goes up to 4 only. I tried your way lightgrav, but it's not right. Is there any other way to work this out?

Note: You'll need the Normal Distribution Table. A certain type of light bulb has a lifetime in hours which is normally distributed with mean μ=650 and standard deviation σ=40. What is the probablility that a randomly selected light bulb has a lifetime in the range (700, 850)? Now this is...

okay, y = \sqrt {x+2}, is rearranged to x = y^2-2. y = (x+2)^4 is rearranged to x = y^(1/4)-2 Then, [(y^2-2)-(y^(1/4)-2)]^2 Then you get y^4-y^2+y^(1/16) But shouldn't you just integrate from the same bounds because your only changing the values of the x-axis.

I'm not sure how I can make it clearer, but when you rearrange y = \sqrt {x+2}, you get x^2 = y^4-4y^2+4. When you rearrange y = (x+2)^4, you get x^2 = y-4y^(1/4)+4 For the latter, that is the 4th root for the 2nd term.

Okay, the bounds move, but that results in an undefined answer, if my expansion above is correct. Shouldn't it be y= 2,1. You can't get a negative answer from those equations.

I can't seem to get the answer. I'm using the 2nd method. I'm meant to be rotating about the y-axis, aren't I? In that case, x^2=(y^2-2)^2------------- x^2=((y^1/4)-2)^2 =y^4-4y^2+4 --------------= y-(4y1/4)+4 Then you integrate these? The bounds are y=0, y=1. But I end up with...

Thanks for your help :smile:

Could someone please explain how to do this question. Find the volume of the solid formed when the area between y=√x and y=x^4 is rotated about the line x=2. I know how to do this when it's rotated about the x and y axes, but I'm not sure how to do it with a different line. Thank you.

Thank you so much salty dog :) Could you also help lead me in the right direction for this question if you don't mind. One of the components of the mediums in which worms are grown is called S basal. It is composed of 0.1M NaCl, 0.05M potassium phosphate and 0.0005% (w/v) cholesterol. You...

Thanks. I just have one more question. A solution requires 250mL of a 7.5% tri sodium citrate. The only cirate you have available is the dihydrate C6H5O7Na3.2H2O with a formula weight of 294.1. How much would you have to weigh out to make up this solution? I'm not sure how to do this...

I just wanted to see if I'm doing this right. Sulfuric acid is supplied as a concentrated liquid. A bottle was assayed and found to have a density of 1.84 g/mL and a purity of 97%. The molecular weight of H2SO4 is 98. What is the molarity of this solution? molarity=moles/volume...

Don't know if anyone's mentioned this. August 27th is the night Mars will be at it's brightest. It'll be about the same size as the moon because it is at it's closest distance from the earth. Maybe I mentioned this too early. :blushing:

I'm not sure ow to do this question. Calculate the reduction potential of a half-cell consisting of a platinum electrode immersed in a 2.0M Fe2+ and 0.2M Fe3+ solution 25c. Thanks.

Does anyone know how to do questions 2 and 3 (particularly 2)?

Ok, I get it. Thanks.